Exhibit s.4

The information in this preliminary prospectus supplement is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This preliminary prospectus supplement is not an offer to sell these securities and is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

[FORM OF PROSPECTUS SUPPLEMENT TO BE USED IN

CONJUNCTION WITH FUTURE RIGHTS OFFERINGS]

PROSPECTUS SUPPLEMENT

(to Prospectus dated            , 2015)

Up to            Shares of Common Stock

Issuable Upon Exercise of Rights

to Subscribe for Such Shares

We are an internally-managed, non-diversified closed-end management investment company that has elected to be regulated as a business development company under the Investment Company Act of 1940, as amended. Our investment objective is to maximize our portfolio total return by generating current income from our debt investments and capital appreciation from our equity-related investments.

We are issuing [transferable/non-transferable] subscription rights to our stockholders of record as of 5:00 p.m., New York City time, on            ,    entitling the holders thereof to subscribe for an aggregate of        shares of our common stock. Record date stockholders will receive one right for each outstanding share of common stock owned on the record date. The rights entitle the holders to purchase one new share of common stock for every rights held. [In addition, record date stockholders who fully exercise their rights will be entitled to subscribe, subject to the limitations described in this prospectus supplement and subject to allotment, for additional shares that remain unsubscribed as a result of any unexercised rights.]    [In addition, any non-record date stockholder who exercises rights is entitled to subscribe for remaining shares that are not otherwise subscribed for by record date stockholders, subject to the limitations described in this prospectus supplement and subject to allotment.]

Our common stock is traded on New York Stock Exchange, or NYSE, under the symbol “HTGC”. The last reported closing price for our common stock on            ,    was $        per share. [The rights are transferable and will be listed for trading on the NYSE under the symbol “             .”]

The subscription price will be [describe means of computing subscription price]. The offer will expire at 5:00 p.m., New York City time, on            ,        , unless extended as described in this prospectus supplement. We, in our sole discretion, may extend the period for exercising the subscription rights. You will have no right to rescind your subscriptions after receipt of your payment of the estimated subscription price except as described in this prospectus supplement.

Please read this prospectus supplement, and the accompanying prospectus, before investing, and keep it for future reference. The prospectus supplement and the accompanying prospectus contain important information about us that a prospective investor should know before investing in our preferred stock. We file annual, quarterly and current reports, proxy statements and other information about us with the Securities and Exchange Commission. This information is available free of charge by contacting us at 400 Hamilton Avenue, Suite 310, Palo Alto, California 94301, or by telephone by calling collect at (650) 289-3060 or on our website at www.herculestech.com. The information on our website is not incorporated by reference into this prospectus or the accompanying prospectus. The SEC also maintains a website at www.sec.gov that contains such information.

An investment in our common stock involves risks, including the risk of a total loss of investment. In addition, the companies in which we invest are subject to special risks. See “Risk Factors” beginning on page 11 of the accompanying prospectus and page S-15 in this prospectus supplement to read about risks you should consider before investing in our securities, including the risk of leverage.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

(1) Estimated on the basis of [describe means of computing subscription price]. See “The Offer—Subscription Price.”

[(2) In connection with this offering,                    , the dealer manager for this offering, will receive a fee for its financial advisory, marketing and soliciting services equal to        % of the subscription price per share for each share issued pursuant to the exercise of rights[, including pursuant to the over-subscription privilege].]

(3) We estimate that we will incur offering expenses of approximately $        in connection with this offering. We estimate that net proceeds to us after expenses will be $        assuming all of the rights are exercised at the estimated subscription price.

(4) Assumes all rights are exercised at the estimated subscription price.

The date of this prospectus supplement is                , 2015

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As a result of the terms of this offering, stockholders who do not fully exercise their rights will own, upon completion of this offer, a smaller proportional interest in us than they owned prior to the offering. [In addition, because the subscription price per share will likely be less than the net asset value per share, based on our current market price, the offer will likely result in an immediate dilution of net asset value per share for all of our stockholders.] This offering will also cause dilution in the distributions per share we are able to distribute subsequent to completion of the offering. Such dilution is not currently determinable because it is not known how many shares will be subscribed for, what the net asset value or market price of our common stock will be on the expiration date for the offer or what the subscription price will be. If the subscription price per share is substantially less than the current net asset value per share, such dilution could be substantial. Any such dilution will disproportionately affect non-exercising stockholders. [If the subscription price is less than our net asset value per share, then all stockholders will experience a decrease in the net asset value per share held by them, irrespective of whether they exercise all or any portion of their rights]. [See “Risk Factors—Your economic and voting interest in us, as well as your proportionate interest in our net asset value, may be diluted as a result of this rights offering” and “Dilution” in this prospectus supplement for more information.]

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ABOUT THIS PROSPECTUS SUPPLEMENT

You should rely only on the information contained in this prospectus supplement and the accompanying prospectus. Neither we nor the underwriters have authorized any other person to provide you with different information from that contained in this prospectus supplement or the accompanying prospectus. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus supplement and the accompanying prospectus do not constitute an offer to sell, or a solicitation of an offer to buy, our securities by any person in any jurisdiction where it is unlawful for that person to make such an offer or solicitation or to any person in any jurisdiction to whom it is unlawful to make such an offer or solicitation. The information contained in this prospectus supplement and the accompanying prospectus is complete and accurate only as of their respective dates, regardless of the time of their delivery or sale of our securities. This prospectus supplement supersedes the accompanying prospectus to the extent it contains information different from or additional to the information in that prospectus.

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering and also adds to and updates information contained in the accompanying prospectus. The second part is the accompanying prospectus, which gives more general information and disclosure. To the extent the information contained in this prospectus supplement differs from the information contained in the accompanying prospectus, the information in this prospectus supplement shall control. You should read this prospectus supplement and the accompanying prospectus together with the additional information described under the heading, “Available Information” before investing in our securities.

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TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

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PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights some of the information in this prospectus supplement and may not contain all of the information that is important to you. For a more complete understanding of this offering, we encourage you to read this entire prospectus supplement and the accompanying prospectus and the documents that are referenced in this prospectus supplement and the accompanying prospectus, together with any accompanying supplements. In this prospectus supplement and the accompanying prospectus, unless the context otherwise requires, the “Company,” “Hercules Technology Growth Capital,” “Hercules,” “we,” “us” and “our” refer to Hercules Technology Growth Capital, Inc. and our wholly-owned subsidiaries.

Our Company

We are a specialty finance company focused on providing senior secured loans to venture capital-backed companies in technology-related industries, including technology, biotechnology, life science and energy and renewables technology, at all stages of development. Our investment objective is to maximize our portfolio total return by generating current income from our debt investments and capital appreciation from our equity-related investments. We are an internally-managed, non-diversified closed-end investment company that has elected to be regulated as a business development company under the Investment Company Act of 1940, as amended, or the 1940 Act. We have qualified as and have elected to be treated for tax purposes as a regulated investment company, or RIC, under the Internal Revenue Code of 1986, as amended, or the Code.

As of [            ], 20[     ], our total assets were approximately $[        ], of which our investments comprised $[        ] at fair value and $[        ] at cost. Since inception through [            ], 20[    ], we have made debt and equity commitments of approximately $[        ] to our portfolio companies.

We also make investments in qualifying small businesses through two wholly-owned, small business investment company, or SBIC, subsidiaries, Hercules Technology II, L.P., or HT II, and Hercules Technology III, L.P., or HT III. At [        ], 20[    ], we have issued $[        ] in Small Business Administration, or SBA, guaranteed debentures in our SBIC subsidiaries. See “Regulation-Small Business Administration Regulations” in the accompanying prospectus for additional information regarding our SBIC subsidiaries.

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As of [            ], 20___, our investment professionals, including Manuel A. Henriquez, our co-founder, Chairman, President and Chief Executive Officer, are currently comprised of [            ] professionals who have, on average, more than [            ] years of experience in venture capital, structured finance, commercial lending or acquisition finance with the types of technology-related companies that we are targeting. We believe that we can leverage the experience and relationships of our management team to successfully identify attractive investment opportunities, underwrite prospective portfolio companies and structure customized financing solutions.

The following chart shows the ownership structure and relationship of certain entities with us.

Our Market Opportunity

We believe that technology-related companies compete in one of the largest and most rapidly growing sectors of the U.S. economy and that continued growth is supported by ongoing innovation and performance improvements in technology products as well as the adoption of technology across virtually all industries in response to competitive pressures. We believe that an attractive market opportunity exists for a specialty finance company focused primarily on investments in structured debt with warrants in technology-related companies for the following reasons:

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Technology-Related Companies are Underserved by Traditional Lenders. We believe many viable technology-related companies backed by financial sponsors have been unable to obtain sufficient growth financing from traditional lenders, including financial services companies such as commercial banks and finance companies because traditional lenders have continued to consolidate and have adopted a more risk-averse approach to lending. More importantly, we believe traditional lenders are typically unable to underwrite the risk associated with these companies effectively.

The unique cash flow characteristics of many technology-related companies, which typically include significant research and development expenditures and high projected revenue growth thus often making such companies difficult to evaluate from a credit perspective. In addition, the balance sheets of these companies often include a disproportionately large amount of intellectual property assets, which can be difficult to value. Finally, the speed of innovation in technology and rapid shifts in consumer demand and market share add to the difficulty in evaluating technology-related companies.

Due to the difficulties described above, we believe traditional lenders are generally refraining from entering the structured debt financing marketplace, instead preferring the risk-reward profile of asset based lending. Traditional lenders generally do not have flexible product offerings that meet the needs of technology-related companies. The financing products offered by traditional lenders typically impose on borrowers many restrictive covenants and conditions, including limiting cash outflows and requiring a significant depository relationship to facilitate rapid liquidation.

Unfulfilled Demand for Structured Debt Financing to Technology-Related Companies. Private debt capital in the form of structured debt financing from specialty finance companies continues to be an important source of funding for technology-related companies. We believe that the level of demand for structured debt financing is a function of the level of annual venture equity investment activity.

We believe that demand for structured debt financing is currently underserved. The venture capital market for the technology-related companies in which we invest has been active and is continuing to show signs of increased investment activity. In addition, lending requirements of traditional lenders have recently become more stringent due to the significant write-offs in the financial services sector, the re-pricing of credit risk in the broadly syndicated market and the financial turmoil affecting the banking system and financial market, which have negatively impacted the debt and equity capital market in the United States and most other markets. At the same time, the venture capital market for the technology-related companies in which we invest has continued to be active. Therefore, to the extent we have capital available, we believe this is an opportune time to be active in the structured lending market for technology-related companies.

Structured Debt with Warrants Products Complement Equity Financing From Venture Capital and Private Equity Funds. We believe that technology-related companies and their financial sponsors will continue to view structured debt securities as an attractive source of capital because it augments the capital provided by venture capital and private equity funds. We believe that our structured debt with warrants product provides access to growth capital that otherwise may only be available through incremental investments by existing equity investors. As such, we provide portfolio companies and their financial sponsors with an opportunity to diversify their capital

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sources. Generally, we believe technology-related companies at all stages of development target a portion of their capital to be debt in an attempt to achieve a higher valuation through internal growth. In addition, because financial sponsor-backed companies have reached a more mature stage prior to reaching a liquidity event, we believe our investments could provide the debt capital needed to grow or recapitalize during the extended period prior to liquidity events.

Our Business Strategy

Our strategy to achieve our investment objective includes the following key elements:

Leverage the Experience and Industry Relationships of Our Management Team and Investment Professionals. We have assembled a team of experienced investment professionals with extensive experience as venture capitalists, commercial lenders and originators of structured debt and equity investments in technology-related companies.

Mitigate Risk of Principal Loss and Build a Portfolio of Equity-Related Securities. We expect that our investments have the potential to produce attractive risk adjusted returns through current income, in the form of interest and fee income, as well as capital appreciation from equity-related securities. We seek to mitigate the risk of loss on our debt investments through the combination of loan principal amortization, cash interest payments, relatively short maturities (generally 12-60 months), security interests in the assets of our portfolio companies, and, on select investments, covenants requiring prospective portfolio companies to have certain amounts of available cash at the time of our investment and the continued support from a venture capital or private equity firm at the time we make our investment.

Provide Customized Financing Complementary to Financial Sponsors’ Capital. We offer a broad range of investment structures and possess expertise and experience to effectively structure and price investments in technology-related companies.

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Invest at Various Stages of Development. We provide growth capital to technology-related companies at all stages of development, including select publicly listed companies and select special opportunity lower middle market companies that require additional capital to fund acquisitions, recapitalization and refinancing, and established-stage companies.

Benefit from Our Efficient Organizational Structure. We believe that our corporate structure enables us to be a long-term partner for our portfolio companies in contrast to traditional investment funds, which typically have a limited life. In addition, because of our access to the equity markets, we believe that we may benefit from a lower cost of capital than that available to private investment funds.

Deal Sourcing Through Our Proprietary Database. We have developed a proprietary and comprehensive structured query language-based (SQL) database system to track various aspects of our investment process including sourcing, originations, transaction monitoring and post-investment performance.

Recent Developments

[Insert description of recent developments at time of offering.]

General Information

Our principal executive offices are located at 400 Hamilton Avenue, Suite 310, Palo Alto, California 94301, and our telephone number is (650) 289-3060. We also have offices in Boston, MA, New York, NY, McLean, VA and Radnor, PA. We maintain a website on the Internet at www.htgc.com. Information contained in our website is not incorporated by reference into this prospectus, and you should not consider that information to be part of this prospectus.

We file annual, quarterly and current periodic reports, proxy statements and other information with the SEC under the Securities Exchange Act of 1934, which we refer to as the Exchange Act. This information is available at the SEC’s public reference room at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information about the operation of the SEC’s public reference room by calling the SEC at (202) 551-8090. In addition, the SEC maintains an Internet website, at www.sec.gov, that contains reports, proxy and information statements, and other information regarding issuers, including us, who file documents electronically with the SEC.

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THE RIGHTS OFFERING

The Offer

We are issuing to stockholders of record, or record date stockholders, on         ,         , or the record date, one [transferable/non-transferable] right for each share of our common stock held on the record date. Each holder of the rights, or rights holder, is entitled to subscribe for one share of our common stock for every         rights held [, which we refer to as the primary subscription right]. We will not issue fractional shares of our common stock upon the exercise of rights; accordingly, rights may be exercised only in multiples of .

[The rights are transferable and will be listed for trading on the NYSE under the symbol “        ” during the course of this offer. See “The Offer.”]

Subscription Price

The subscription price per share will be [describe means of computing subscription price]. [Because the subscription price will be determined on the expiration date, rights holders who decide to acquire shares pursuant to the primary subscription right or pursuant to the over-subscription privilege will not know the actual purchase price of those shares when they make that decision.] See “The Offer—Subscription Price.”

[Over-Subscription Privilege

Record date stockholders who fully exercise all rights issued to them (other than those rights which cannot be exercised because they represent the right to acquire less than one share) are entitled to subscribe for additional shares of our common stock which were not subscribed for by other stockholders, which we refer to as the remaining shares. If sufficient remaining shares of our common stock are available, all record date stockholders’ over-subscription requests will be honored in full. In addition, any non-record date stockholder who exercises rights is entitled to subscribe for remaining shares that are not otherwise subscribed for by record date stockholders. Shares acquired pursuant to the over-subscription privilege are subject to certain limitations and pro rata allocations. See “The Offer—Over-Subscription Privilege.”]

Purpose of the Offer

Our board of directors has determined that it would be in the best interest of the Company and its stockholders to increase the capital available for making additional investments, as well as to pay operating expenses, temporarily repay debt and generally enhance our liquidity. We believe that we must have sufficient liquidity available to remain a credible source of capital. The offering will increase the capital available for us to make additional investments. This offering gives existing stockholders the right to purchase additional shares at a price that is expected to be below market without incurring any commission or charge, while providing us access to additional capital resources. In connection with the approval of this rights offering, our board of directors considered, among other things, the following factors:

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There can be no assurance of the amount of dilution that a stockholder will experience or that the rights offering will be successful.

[The purpose of setting the determination of the subscription price upon the expiration of the offer is to attract the maximum participation of stockholders in the offer, with minimum dilution to non-participating stockholders.]

[The transferable rights will allow non-participating stockholders the potential of receiving cash payment upon the sale of the rights, receipt of which may be viewed as partial compensation for the dilution of their interests.]

We cannot assure you that the current offering will be successful, or that by increasing the amount of our available capital, our aggregate expenses and, correspondingly, our expense ratio will be lowered.

[In determining that this offer is in our best interest and in the best interests of our stockholders, we have retained             , the dealer manager for this offer, to provide us with financial advisory, marketing and soliciting services relating to this offer, including advice with respect to the structure, timing and terms of the offer. In this regard, our board of directors considered, among other things, using a fixed pricing versus variable pricing mechanism, the benefits and drawbacks of conducting a non-transferable versus a transferable rights offering, the effect on us if this offer is not fully subscribed and the experience of the dealer manager in conducting rights offerings.]

[Although we have no present intention to do so, we may, in the future and in our discretion, choose to make additional rights offerings from time to time for a number of shares and on terms which may or may not be similar to this offer, provided that our board of directors must determine that each subsequent rights offering is in the best interest of our stockholders. Any such future rights offering will be made in accordance with the 1940 Act.]

[Sale of Rights

The rights are evidenced by a subscription certificate and are transferable until         ,         (or if the offer is extended, until the extended expiration date). The rights will be listed for trading on the NYSE under the symbol “        ” . We and the dealer manager will use our best efforts to ensure that an adequate trading market for the rights will exist. However, no assurance can be given that a market for the rights will develop. Trading in the rights on the NYSE may be conducted until close of trading on the NYSE on         ,         (or, if the offer is extended, until the extended expiration date). See “The Offer—Sale of Rights.”]

How to Obtain Subscription Information

How to Subscribe

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Subscription Agent

will act as the subscription agent in connection with this offer.

Information Agent

will act as the information agent in connection with this offer. You may contact         toll-free with questions at         . Broker-dealers and nominees may call .

[Distribution Arrangements

will act as dealer manager for the offer. Under the terms and subject to the conditions contained in the dealer manager agreement, the dealer manager will provide financial advisory services and marketing assistance in connection with the offer and will solicit the exercise of rights and participation in the over-subscription privilege by our stockholders. The offer is not contingent upon any number of rights being exercised. We have agreed to pay the dealer manager a fee for its financial advisory, marketing and soliciting services equal to % of the subscription price per share for shares issued pursuant to the exercise of rights, including pursuant to the over-subscription privilege. The dealer manager may re-allow a portion of its fees to other broker-dealers that have assisted in soliciting the exercise of rights.]

Important Dates to Remember

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FEES AND EXPENSES

The following table is intended to assist you in understanding the various costs and expenses that an investor in our securities will bear directly or indirectly. However, we caution you that some of the percentages indicated in the table below are estimates and may vary. The following table and example should not be considered a representation of our future expenses. Actual expenses may be greater or less than shown. Except where the context suggests otherwise, whenever this prospectus contains a reference to fees or expenses paid by “you” or “us” or that “we” will pay fees or expenses, stockholders will indirectly bear such fees or expenses as investors in the Company.

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Example

The following example demonstrates the projected dollar amount of total cumulative expenses that would be incurred over various periods with respect to a $1,000 hypothetical investment in our common stock, assuming a 5% annual return. These amounts are based upon our payment of annual operating expenses at the levels set forth in the table above and assume no additional leverage.

The example and the expenses in the tables above should not be considered a representation of our future expenses, and actual expenses may be greater or lesser than those shown. Moreover, while the example assumes, as required by the applicable rules of the SEC, a 5% annual return, our performance will vary and may result in a return greater or lesser than 5%. In addition, while the example assumes reinvestment of all dividends and distributions at net asset value, participants in our dividend reinvestment plan may receive shares valued at the market price in effect at that time. This price may be at, above or below net asset value. See “Dividend Reinvestment Plan” in the accompanying prospectus for additional information regarding our dividend reinvestment plan.

This example and the expenses in the table above should not be considered a representation of our future expenses as actual expenses (including the cost of debt, and other expenses) may be greater or less than those shown.

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RISK FACTORS

Investing in our securities involves a number of significant risks. Before you invest in our securities, you should be aware of various risks, including those described below and those set forth in the accompanying prospectus. You should carefully consider these risk factors, together with all of the other information included in this prospectus supplement and the accompanying prospectus, before you decide whether to make an investment in our securities. The risks set out below are not the only risks we face. Additional risks and uncertainties not presently known to us or not presently deemed material by us may also impair our operations and performance. If any of the following events occur, our business, financial condition, results of operations and cash flows could be materially and adversely affected. In such case, our net asset value and the trading price of our common stock could decline, and you may lose all or part of your investment. The risk factors described below, together with those set forth in the accompanying prospectus, are the principal risk factors associated with an investment in us as well as those factors generally associated with an investment company with investment objectives, investment policies, capital structure or trading markets similar to ours.

[The rights are non-transferable and there is no market for the rights.

Other than in very limited circumstances, you may not sell, give away or otherwise transfer your rights. Because the rights are non-transferable, there is no market or other means for you to directly realize any value associated with the rights. You must exercise the rights and acquire additional shares of our common stock to realize any value.]

Your economic and voting interest in us, as well as your proportionate interest in our net asset value, may be diluted as a result of this rights offering.

Stockholders who do not fully exercise their rights should expect that they will, at the completion of the offer, own a smaller proportional interest in us, including with respect to voting rights, than would otherwise be the case if they fully exercised their rights. We cannot state precisely the amount of any such dilution in share ownership because we do not know at this time what proportion of the shares will be purchased as a result of the offer.

In addition, if the subscription price is less than our net asset value per share, then our stockholders would experience an immediate dilution of the aggregate net asset value of their shares as a result of the offer. The amount of any decrease in net asset value is not predictable because it is not known at this time what the subscription price and net asset value per share will be on the expiration date of the rights offering or what proportion of the shares will be purchased as a result of the offer. Such dilution could be substantial.

This offering will also cause dilution in the dividends per share we are able to distribute subsequent to completion of the offering. In addition, our reported earnings per share will be retroactively adjusted to reflect the dilutive effects of this offering. See “Dilution.”]

[Insert any additional relevant risk factors not included in the base prospectus.]

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

The matters discussed in this prospectus supplement and the accompanying prospectus, as well as in future oral and written statements by management of Hercules Technology Growth Capital, Inc., that are forward-looking statements are based on current management expectations that involve substantial risks and uncertainties which could cause actual results to differ materially from the results expressed in, or implied by, these forward-looking statements. Forward-looking statements relate to future events or our future financial performance. We generally identify forward-looking statements by terminology such as “may,” “will,” “should,” “expects,” “plans,” “anticipates,” “could,” “intends,” “target,” “projects,” “contemplates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negative of these terms or other similar words. Important assumptions include our ability to originate new investments, achieve certain margins and levels of profitability, the availability of additional capital, and the ability to maintain certain debt to asset ratios and our outlook on the economy and its effect on venture capital. In light of these and other uncertainties, the inclusion of a projection or forward-looking statement in this prospectus supplement and the accompanying prospectus should not be regarded as a representation by us that our plans or objectives will be achieved. The forward-looking statements contained in this prospectus supplement and the accompanying prospectus include statements as to:

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For a discussion of factors that could cause our actual results to differ from forward-looking statements contained in this prospectus supplement and the accompanying prospectus, please see the discussion under “Risk Factors” in both this prospectus supplement and the accompanying prospectus. You should not place undue reliance on these forward-looking statements. The forward-looking statements made in this prospectus supplement and the accompanying prospectus relate only to events as of the date on which the statements are made. The forward-looking statements contained herein are excluded from the safe harbor protection provided by Section 27A of the Securities Act of 1933.

Industry and Market Data

This prospectus supplement and the accompanying prospectus contain third-party estimates and data regarding valuations of venture capital-backed companies. This data was reported by Dow Jones VentureSource, an independent venture capital industry research company which we refer to as VentureSource. VentureSource is commonly relied upon as an information source in the venture capital industry. Although we have not independently verified any such data, we believe that the industry information contained in such releases and data tables and included in this prospectus supplement and the accompanying prospectus is reliable.

We have compiled certain industry estimates presented in this prospectus supplement and the accompanying prospectus from internally generated information and data. While we believe our estimates are reliable, they have not been verified by any independent sources. The estimates are based on a number of assumptions, including increasing investment in venture capital and private equity-backed companies. Actual results may differ from projections and estimates, and this market may not grow at the rates projected, or at all. If this market fails to grow at projected rates, our business and the market price of our common stock could be materially adversely affected.

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USE OF PROCEEDS

We estimate that net proceeds we will receive from this offering will be approximately $             million assuming all of the rights are exercised at the estimated subscription price and after deducting payments to the dealer manager of     % of the subscription price for each share issued pursuant to exercise of the rights and estimated offering expenses of approximately $             payable by us.

We expect to use the net proceeds from this offering to fund investments in debt and equity securities in accordance with our investment objective and for other general corporate purposes.

We intend to seek to invest the net proceeds received in this offering as promptly as practicable after receipt thereof consistent with our investment objective. We anticipate that substantially all of the net proceeds from any offering of our securities will be used as described above within three to six months, depending on market conditions. We anticipate that the remainder will be used for working capital and general corporate purposes, including potential payments or distributions to shareholders. Pending such use, we will invest a portion of the net proceeds of this offering in short-term investments, such as cash and cash equivalents, which we expect will earn yields substantially lower than the interest income that we anticipate receiving in respect of investments in accordance with our investment objective.

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CAPITALIZATION

The following table sets forth (i) our actual capitalization as of             , 20     , and (ii) our capitalization as adjusted to give effect to the sale of our securities in this offering, assuming all rights are exercised at the estimated subscription price of $         and our receipt of the estimated net proceeds from that sale. You should read this table together with “Use of Proceeds” and our statement of assets and liabilities included elsewhere in this prospectus supplement.

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DILUTION

As of             ,             , our net assets were $             million, or approximately $         per share. After giving effect to the sale of             shares of our common stock in this offering, assuming all rights are exercised at the estimated subscription price of $         per share, and our receipt of the estimated net proceeds from that sale, our pro forma net asset value would have been approximately $         million, or approximately $         per share, representing an immediate dilution of approximately $         per share to our existing stockholders.

The following table illustrates the dilutive effects of this offering on a per share basis, assuming all rights are exercised at the estimated subscription price of $         per share:

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PRICE RANGE OF COMMON STOCK

Our common stock is traded on the New York Stock Exchange under the symbol “HTGC.”

The following table sets forth the range of high and low sales prices of our common stock as reported on the NYSE, the sales price as a percentage of net asset value and the dividends declared by us for each fiscal quarter. The stock quotations are interdealer quotations and do not include markups, markdowns or commissions.

The last reported price for our common stock on [            ], 20__ was $[            ] per share.

Shares of business development companies may trade at a market price that is less than the value of the net assets attributable to those shares. The possibility that our shares of common stock will trade at a discount from net asset value or at premiums that are unsustainable over the long term are separate and distinct from the risk that our net asset value will decrease. At times, our shares of common stock have traded at a premium to net asset value and at times our shares of common stock have traded at a discount to the net assets attributable to those shares. It is not possible to predict whether the shares offered hereby will trade at, above, or below net asset value.

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Dividends

The following table summarizes our dividends declared and paid or to be paid on all shares, including restricted stock, to date:

On May 4, 2015 the Board of Directors declared a cash dividend of $0.31 per share to be paid on May 25, 2015 to shareholders of record as of May 18, 2015. This dividend represents our thirty-ninth consecutive dividend declaration since our initial public offering, bringing the total cumulative dividend declared to date $10.61 per share.

Our Board of Directors maintains a variable dividend policy with the objective of distributing four quarterly distributions in an amount that approximates 90—100% of our taxable quarterly income or potential annual income for a particular year. In addition, at the end of the year, we may also pay an additional special dividend or fifth dividend, such that we may distribute approximately all of our annual taxable income in the year it was earned, while maintaining the option to spill over our excess taxable income.

Distributions in excess of our current and accumulated earnings and profits would generally be treated first as a return of capital to the extent of the stockholder’s tax basis, and any remaining distributions would be treated as a capital gain. The determination of the tax attributes of our distributions is made annually as of the end of our fiscal year based upon our taxable income for the full year and distributions paid for the full year, therefore a determination made on a quarterly basis may not be representative of the tax attributes of our 20     distributions to stockholders. If we had determined the tax attributes of our distributions year-to-date as of                     , 20    , approximately     % would be from ordinary income and spillover earnings from 20    , and     % would be a return of capital.

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We intend to distribute quarterly dividends to our stockholders. In order to avoid certain excise taxes imposed on RICs, we currently intend to distribute during each calendar year an amount at least equal to the sum of (1) 98% of our ordinary income for the calendar year, (2) 98.2% of our capital gains in excess of capital losses for the one year period ending on October 31 of the calendar year, and (3) any ordinary income and net capital gains for the preceding year that were not distributed during such year. We will not be subject to excise taxes on amounts on which we are required to pay corporate income tax (such as retained net capital gains). In order to obtain the tax benefits applicable to RICs, we will be required to distribute to our stockholders with respect to each taxable year at least 90% of our ordinary income and realized net short-term capital gains in excess of realized net long-term capital losses.

We can offer no assurance that we will achieve results that will permit the payment of any cash distributions and, if we issue senior securities, we will be prohibited from making distributions if doing so causes us to fail to maintain the asset coverage ratios stipulated by the 1940 Act or if distributions are limited by the terms of any of our borrowings. See “Regulation” in the accompanying prospectus.

We maintain an “opt-out” dividend reinvestment plan for our common stockholders. As a result, if we declare a dividend, cash dividends will be automatically reinvested in additional shares of our common stock unless the stockholder specifically “opts out” of the dividend reinvestment plan and chooses to receive cash dividends. See “Dividend Reinvestment Plan” in the accompanying prospectus.

Our ability to make distributions will be limited by the asset coverage requirements under the 1940 Act.

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THE OFFER

Purpose of the Offer

Our board of directors has determined that it would be in the best interests of Company and its stockholders to increase the capital available for making additional investments, as well as to pay operating expenses, temporarily repay debt and generally enhance our liquidity. We believe that we must have sufficient liquidity available to remain a credible source of capital. The offering will increase the capital available for us to make additional investments. The current offering gives existing stockholders the right to purchase additional shares at a price that is expected to be below market without incurring any commission or charge, while providing us access to such additional capital resources. In connection with the approval of this rights offering, our board of directors considered, among other things, the following factors:

There can be no assurance of the amount of dilution that a stockholder will experience or that the rights offering will be successful.

The purpose of setting the determination of the subscription price upon the expiration of the offer is to attract the maximum participation of stockholders in the offer, with minimum dilution to non-participating stockholders.

[The transferable rights will allow non-participating stockholders the potential of receiving cash payment upon the sale of the rights, receipt of which may be viewed as partial compensation for the dilution of their interests.]

We cannot assure you that the current offering will be successful, or that by increasing the size of our available equity capital, our aggregate expenses and, correspondingly, our expense ratio will be lowered.

[In determining that this offer was in our best interest and in the best interests of our stockholders, we have retained             , the dealer manager for this offering, to provide us with financial advisory, marketing and soliciting services relating to this offer, including advice with respect to the structure, timing and terms of the offer. In this regard, our board of directors considered, among other things, using a fixed pricing versus variable pricing

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mechanism, the benefits and drawbacks of conducting a non-transferable versus a transferable rights offering, the effect on us if this offer is not fully subscribed and the experience of the dealer manager in conducting rights offerings.]

[Although we have no present intention to do so, we may, in the future and in our discretion, choose to make additional rights offerings from time to time for a number of shares and on terms which may or may not be similar to this offer, provided that our board of directors must determine that each subsequent rights offering is in the best interest of our stockholders. Any such future rights offering will be made in accordance with the 1940 Act.]

Terms of the Offer

We are issuing to record date stockholders [transferable/non-transferable] rights to subscribe for up to approximately                 shares. Each record date stockholder is being issued one [transferable/non-transferable] right for each whole share owned on the record date. The rights entitle each holder, or rights holder, to acquire at the subscription price one share for every             rights held [, which we refer to as the primary subscription right]. Rights may be exercised at any time during the subscription period, which commences on             ,     , the record date, and ends at 5:00 p.m., New York City time, on             ,     , the expiration date, unless extended by us.

The rights are [transferable and will be listed for trading on the NYSE under the symbol “             “ during the course of the offer/non-transferable]. The shares of our common stock issued pursuant to an exercise of rights will be listed on the NYSE under the symbol “HTGC”. The rights will be evidenced by subscription certificates which will be mailed to stockholders, except as discussed below under “—Foreign Stockholders.”

We will not issue fractional shares upon the exercise of rights; accordingly, rights may be exercised only in multiples of .

The rights are [transferable/non-transferable]. [Rights holders who are not record date stockholders may purchase shares as described above, which we refer to as the primary subscription, and may be entitled to subscribe for shares pursuant to the over-subscription privilege (as described below).]

[Shares for which there is no subscription during the primary subscription will be offered, by means of the over-subscription privilege, first to record date stockholders who fully exercise the rights issued to them pursuant to this offering (other than those rights that cannot be exercised because they represent in the aggregate the right to acquire less than one share) and who wish to acquire more than the number of shares they are entitled to purchase pursuant to the exercise of their rights. In addition, any non-record date rights holder who exercises rights is entitled to subscribe for remaining shares that are not otherwise subscribed for by record date stockholders. Shares acquired pursuant to the over-subscription privilege are subject to certain limitations and pro rata allocations. See “—Over-Subscription Privilege” below.]

For purposes of determining the number of shares a record date stockholder may acquire pursuant to the offer, broker-dealers, trust companies, banks or others whose shares are held of record by Cede & Co. (“Cede”) or by any other depository or nominee will be deemed to be the holders of the rights that are issued to Cede or the other depository or nominee on their behalf.

There is no minimum number of rights which must be exercised in order for the offer to close.

[Over-Subscription Privilege

Shares not subscribed for by rights holders, which we refer to as remaining shares, will be offered, by means of the over-subscription privilege, first to record date stockholders who have fully exercised the rights issued to them and who wish to acquire more than the number of shares they are entitled to purchase pursuant to the basic subscription. Rights holders should indicate on the subscription certificate that they submit with respect to the exercise of the rights issued to them how many additional shares they are willing to acquire pursuant to the over-subscription privilege. If there are sufficient remaining shares, all record date stockholders’ over-subscription requests will be honored in full. If record date stockholder requests for shares pursuant to the over-subscription

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privilege exceed the remaining shares available, the available remaining shares will be allocated pro-rata among record date stockholders who over-subscribe based on the number of shares held on the record date. The percentage of remaining shares each over-subscribing stockholder may acquire will be rounded down to result in delivery of whole shares. The allocation process may involve a series of allocations to assure that the total number of remaining shares available for over-subscriptions is distributed on a pro-rata basis. The formula to be used in allocating the remaining shares is as follows:

Any rights holder other than record date stockholders who exercises rights is entitled to subscribe for remaining shares that are not otherwise over-subscribed for by record date stockholders. These non-record date rights holders should indicate in the subscription certificate submitted with respect to the exercise of any rights how many shares they are willing to acquire pursuant to the over-subscription privilege. We cannot assure non-record date rights holders that they will receive shares pursuant to the over-subscription privilege.

If sufficient remaining shares are available after the over-subscription privileges for the record date stockholders have been allotted, then all over-subscriptions by non-record date rights holders will be honored in full. If the remaining shares are insufficient to permit such allocation, the remaining shares will be allocated pro-rata among the non-record date rights holders who wish to exercise their over-subscription privilege, based on the number of rights held by such rights holders on the expiration date. However, if this pro-rata allocation results in any holder being allocated a greater number of shares than the holder subscribed for pursuant to the exercise of the over-subscription privilege, then such holder will be allocated only such number of shares pursuant to the over-subscription privilege as such holder subscribed for. The formula to be used in allocating the shares available to non-record date rights holders exercising their over-subscription privilege is as follows:

Banks, brokers, trustees and other nominee holders of rights will be required to certify to the subscription agent, before any over-subscription privilege may be exercised with respect to any particular beneficial owner, as to the aggregate number of rights exercised pursuant to the primary subscription and the number of shares subscribed for pursuant to the over-subscription privilege by such beneficial owner and that such beneficial owner’s primary subscription was exercised in full. We will not offer or sell in connection with the offer any shares that are not subscribed for pursuant to the primary subscription or the over-subscription privilege.]

Subscription Price

The subscription price for the shares to be issued pursuant to the offer will be [describe means of computing subscription price]. [Since the expiration date will be             ,         (unless we extend the subscription period), rights holders will not know the subscription price at the time of exercise and will be required initially to pay for both the shares subscribed for pursuant to the primary subscription right and, if eligible, any additional shares subscribed for pursuant to the over-subscription privilege at the estimated subscription price of $             per share.] See “—Payment for Shares” below. Rights holders who exercise their rights will have no right to rescind a purchase after receipt of their completed subscription certificates together with payment for shares by the subscription agent. We do not have the right to withdraw the rights or cancel this offer after the rights have been distributed.

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Expiration of the Offer

The offer will expire at 5:00 p.m., New York City time, on             ,         , the expiration date, unless extended by us. The rights will expire on the expiration date of the rights offering and may not be exercised thereafter.

Our board of directors may determine to extend the subscription period, and thereby postpone the expiration date, to the extent our board of directors determines that doing so is in the best interest of our stockholders. For example, our board of directors may elect to extend the subscription period in the event there is substantial instability or volatility in the trading price of our common stock or the rights on the NYSE at or near the expiration date, or if any event occurs which causes trading to cease or be suspended on the NYSE or the financial markets generally. The foregoing are not the only circumstances under which this offer may be extended, and our board of directors is free to extend the subscription period at its discretion, provided it determines that doing so is in the best interests of our stockholders.

Any extension of the offer will be followed as promptly as practicable by announcement thereof, and in no event later than 9:00 a.m., New York City time, on the next business day following the previously scheduled expiration date. Without limiting the manner in which we may choose to make such announcement, we will not, unless otherwise required by law, have any obligation to publish, advertise or otherwise communicate any such announcement other than by issuing a press release or such other means of announcement as we deem appropriate.

Information Agent

            will act as the information agent in connection with the offering. The information agent will receive for its services a fee estimated to be approximately $             plus reimbursement of all out-of-pocket expenses related to the offering. can be contacted at the below address:

Subscription Agent

            will act as the subscription agent in connection with this offer. The subscription agent will receive for its administrative, processing, invoicing and other services a fee estimated to be approximately $            , plus reimbursement for all out-of-pocket expenses related to the offer.

Completed subscription certificates must be sent together with full payment of the subscription price for all shares subscribed for in the primary subscription and pursuant to over-subscription privilege to the subscription agent by one of the methods described below. Alternatively, an Eligible Guarantor Institution may send notices of guaranteed delivery by facsimile to                 which must be received by the subscription agent at or prior to 5:00 p.m., New York City time, on the expiration date of the rights offering. Facsimiles should be confirmed by telephone at                 . We will accept only properly completed and duly executed subscription certificates actually received at any of the addresses listed below, at or prior to 5:00 p.m., New York City time, on the expiration date of the rights offering or by the close of business on the third business day after the expiration date of the rights offering following timely receipt of a notice of guaranteed delivery. See “—Payment for Shares” below. In this prospectus, close of business means 5:00 p.m., New York City time, on the relevant date.

Delivery to an address other than one of the addresses listed above will not constitute valid delivery.

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Any questions or requests for assistance concerning the method of subscribing for shares or for additional copies of this prospectus or subscription certificates or notices of guaranteed delivery may be directed to the information agent at its telephone number and address listed below:

Stockholders may also contact their broker-dealers or nominees for information with respect to the offer.

[Sale of Rights

The Rights are Transferable

The rights will be listed for trading on the NYSE under the symbol “            ” subject to notice of issuance. We and the dealer manager will use our best efforts to ensure that an adequate trading market for the rights will exist, although no assurance can be given that a market for the rights will develop. Trading in the rights on the NYSE is expected to be conducted beginning on or about              ,             , and continuing until             ,             (or if the offer is extended, until the extended expiration date). Rights holders are encouraged to contact their broker-dealer, bank, trustee or other nominees for more information about trading of the rights.

Sales Through Subscription Agent and Dealer Manager

Stockholders who do not wish to exercise any or all of their rights may instruct the subscription agent to sell any rights they do not intend to exercise themselves through or to the dealer manager. Subscription certificates representing the rights to be sold through or to the dealer manager must be received by the subscription agent on or before             ,             (or if the offer is extended, on or before two business days prior to the extended expiration date). Upon the timely receipt by the subscription agent of appropriate instructions to sell rights, the subscription agent will ask the dealer manager either to purchase or to use its best efforts to complete the sale and the subscription agent will remit the proceeds of the sale to the selling stockholders. If the rights can be sold, sales of such rights will be deemed to have been effected at the weighted-average price received by the dealer manager on the day such rights are sold. The sale price of any rights sold to the dealer manager will be based upon the then current market price for the rights. The dealer manager will also attempt to sell all rights which remain unclaimed as a result of subscription certificates being returned by the postal authorities to the subscription agent as undeliverable as of the fourth business day prior to the expiration date of the rights offering. The subscription agent will hold the proceeds from those sales for the benefit of such non-claiming stockholders until such proceeds are either claimed or revert to the state pursuant to applicable state law. There can be no assurance that the dealer manager will purchase or be able to complete the sale of any such rights, and neither we nor the dealer manager has guaranteed any minimum sales price for the rights. If a stockholder does not utilize the services of the subscription agent and chooses to use another broker-dealer or other financial institution to sell rights, then the other broker-dealer or financial institution may charge a fee to sell the rights.

Other Transfers

The rights evidenced by a subscription certificate may be transferred in whole by endorsing the subscription certificate for transfer in accordance with the accompanying instructions. A portion of the rights evidenced by a single subscription certificate (but not fractional rights) may be transferred by delivering to the subscription agent a subscription certificate properly endorsed for transfer, with instructions to register such portion of the rights evidenced thereby in the name of the transferee and to issue a new subscription certificate to the transferee evidencing such transferred rights. In such event, a new subscription certificate evidencing the balance of the rights, if any, will be issued to the stockholder or, if the stockholder so instructs, to an additional transferee. The signature on the subscription certificate must correspond to the name as written upon the face of the subscription certificate in every particular, without alteration or enlargement, or any change. A signature guarantee must be provided by an Eligible Guarantor Institution as that term is defined in Rule 17Ad-15 under the Exchange Act, subject to the standards and procedures adopted by us.

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Stockholders wishing to transfer all or a portion of their rights should allow at least five business days prior to the expiration date of the rights offering for (1) the transfer instructions to be received and processed by the subscription agent, (2) a new subscription certificate to be issued and transmitted to the transferee or transferees with respect to transferred rights, and to the transferor with respect to retained rights, if any, and (3) the rights evidenced by such new subscription certificate to be exercised or sold by the recipients thereof. Neither we nor the subscription agent nor the dealer manager shall have any liability to a transferee or transferor of rights if subscription certificates are not received in time for exercise or sale prior to the expiration date (or if the offer is extended, on or before two business days prior to the extended expiration date) of the rights offering.

Except for the fees charged by the subscription agent [and dealer manager], which will be paid by us, all commissions, fees and other expenses (including brokerage commissions and transfer taxes) incurred or charged in connection with the purchase, sale or exercise of rights will be for the account of the transferor of the rights, and none of those commissions, fees or expenses will be paid by us, the subscription agent or the dealer manager.

We anticipate that the rights will be eligible for transfer through, and that the exercise of the primary subscription and the over-subscription privilege may be effected through, the facilities of the Depository Trust Company, or DTC. Holders of DTC exercised rights may exercise the over-subscription privilege in respect of such DTC exercised rights by properly completing and duly executing and delivering to the subscription agent, at or prior to 5:00 p.m., New York City time, on the day prior to the expiration date of the rights offering, a nominee holder over-subscription certificate or a substantially similar form satisfactory to the subscription agent, together with payment of the subscription price for the number of shares for which the over-subscription privilege is to be exercised.]

Methods for Exercising Rights

Rights are evidenced by subscription certificates that, except as described below under “—Foreign Stockholders,” will be mailed to record date stockholders or, if a record date stockholder’s shares are held by Cede or any other depository or nominee on their behalf, to Cede or such depository or nominee. Rights may be exercised by completing and signing the subscription certificate that accompanies this prospectus and mailing it in the envelope provided, or otherwise delivering the completed and duly executed subscription certificate to the subscription agent, together with payment in full for the shares at the estimated subscription price by the expiration date of the rights offering. Rights may also be exercised by contacting your broker, trustee or other nominee, who can arrange, on your behalf, to guarantee delivery of payment and delivery of a properly completed and duly executed subscription certificate pursuant to a notice of guaranteed delivery by the close of business on the third business day after the expiration date. A fee may be charged for this service. Completed subscription certificates and related payments must be received by the subscription agent prior to 5:00 p.m., New York City time, on or before the expiration date (unless payment is effected by means of a notice of guaranteed delivery as described below under “—Payment for Shares”) at the offices of the subscription agent at the address set forth above. Fractional shares will not be issued upon the exercise of rights.

[Exercise of the Over-Subscription Privilege

Record date stockholders who fully exercise all rights issued to them and rights holders other than record date stockholders, may both participate in the over-subscription privilege by indicating on their subscription certificate the number of shares they are willing to acquire. If sufficient remaining shares are available after the primary subscription, all over-subscriptions will be honored in full; otherwise remaining shares will be allocated first to record date stockholders and then (if any remaining shares are still available) to non-record date rights holders, and the number of remaining shares issued to some or all rights holders participating in the over-subscription privilege may be reduced as described under “—Over-Subscription Privilege” above. ]

Record Date Stockholders Whose Shares Are Held By a Nominee

Record date stockholders whose shares are held by a nominee, such as a bank, broker-dealer or trustee, must contact that nominee to exercise their rights. In that case, the nominee will complete the subscription certificate on behalf of the record date stockholder and arrange for proper payment by one of the methods set forth under “—Payment for Shares” below.

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Nominees

Nominees, such as brokers, trustees or depositories for securities, who hold shares for the account of others, should notify the respective beneficial owners of the shares as soon as possible to ascertain the beneficial owners’ intentions and to obtain instructions with respect to the rights. If the beneficial owner so instructs, the nominee should complete the subscription certificate and submit it to the subscription agent with the proper payment as described under “—Payment for Shares” below.

All questions as to the validity, form, eligibility (including times of receipt and matters pertaining to beneficial ownership) and the acceptance of subscription forms and the subscription price will be determined by us, which determinations will be final and binding. No alternative, conditional or contingent subscriptions will be accepted. We reserve the right to reject any or all subscriptions not properly submitted or the acceptance of which would, in the opinion of our counsel, be unlawful.

We reserve the right to reject any exercise if such exercise is not in accordance with the terms of this rights offering or not in proper form or if the acceptance thereof or the issuance of shares of our common stock thereto could be deemed unlawful. We reserve the right to waive any deficiency or irregularity with respect to any subscription certificate. Subscriptions will not be deemed to have been received or accepted until all irregularities have been waived or cured within such time as we determine in our sole discretion. We will not be under any duty to give notification of any defect or irregularity in connection with the submission of subscription certificates or incur any liability for failure to give such notification.

Foreign Stockholders

Subscription certificates will not be mailed to foreign stockholders. Foreign stockholders will receive written notice of this offer. The subscription agent will hold the rights to which those subscription certificates relate for these stockholders’ accounts until instructions are received to exercise the rights, subject to applicable law. If no instructions have been received by the expiration date, such rights will expire.

Payment for Shares

Participating rights holders may choose between the following methods of payment:

All payments by a participating rights holder must be in U.S. dollars by money order or check or bank draft drawn on a bank or branch located in the United States and payable to Hercules Technology Growth Capital, Inc.

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The subscription agent will deposit all funds received by it prior to the final payment date into a segregated account pending pro-ration and distribution of the shares.

The method of delivery of subscription certificates and payment of the subscription price to us will be at the election and risk of the participating rights holders, but if sent by mail it is recommended that such certificates and payments be sent by registered mail, properly insured, with return receipt requested, and that a sufficient number of days be allowed to ensure delivery to the subscription agent and clearance of payment prior to 5:00 p.m., New York City time, on the expiration date or the date guaranteed payments are due under a notice of guaranteed delivery (as applicable). Because uncertified personal checks may take at least five business days to clear, you are strongly urged to pay, or arrange for payment, by means of certified or cashier’s check or money order.

On a date within business days following the expiration date, the subscription agent will send to each participating rights holder (or, if rights are held by Cede or any other depository or nominee, to Cede or such other depository or nominee) a confirmation showing (1) the number of shares purchased pursuant to the primary subscription, (2) the number of shares, if any, acquired pursuant to the over-subscription privilege, (3) the per share and total purchase price for the shares, and (4) any additional amount payable to us by the participating rights holder or any excess to be refunded by us to the participating rights holder, in each case based on the subscription price as determined on the expiration date. Any additional payment required from a participating rights holder must be received by the subscription agent within ten business days after the confirmation date. Any excess payment to be refunded by us to a participating rights holder will be mailed by the subscription agent to the rights holder as promptly as practicable. No interest will be paid on any amounts refunded.

Whichever of the two methods described above is used, issuance of the shares purchased is subject to collection of checks and actual payment. If a participating rights holder who subscribes for shares pursuant to the primary subscription or over-subscription privilege does not make payment of any amounts due by the expiration date, the date guaranteed payments are due under a notice of guaranteed delivery or within ten business days of the confirmation date, as applicable, the subscription agent reserves the right to take any or all of the following actions: (1) reallocate the shares to other participating rights holders in accordance with the over-subscription privilege; (2) apply any payment actually received by it from the participating rights holder toward the purchase of the greatest whole number of shares which could be acquired by such participating rights holder upon exercise of the primary subscription and/or the over-subscription privilege; and/or (3) exercise any and all other rights or remedies to which it may be entitled, including the right to set off against payments actually received by it with respect to such subscribed for shares.

All questions concerning the timeliness, validity, form and eligibility of any exercise of rights will be determined by us, whose determinations will be final and binding. We in our sole discretion may waive any defect or irregularity, or permit a defect or irregularity to be corrected within such time as we may determine, or reject the purported exercise of any right. Subscriptions will not be deemed to have been received or accepted until all irregularities have been waived or cured within such time as we determine in our sole discretion. The subscription agent will not be under any duty to give notification of any defect or irregularity in connection with the submission of subscription certificates or incur any liability for failure to give such notification.

Participating rights holders will have no right to rescind their subscription after receipt of their payment for shares by the subscription agent, except as provided below under “—Notice of Net Asset Value Decline.”

Notice of Net Asset Value Decline

We will suspend the offer until we amend this prospectus if, subsequent to the effective date of this prospectus, our net asset value declines more than 10% from our net asset value as of that date. Accordingly, the expiration date would be extended and we would notify record date stockholders of the decline and permit participating rights holders to cancel their exercise of rights.

Delivery of Stock Certificates

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Participants in our dividend reinvestment plan will have any shares that they acquire pursuant to the offer credited to their stockholder dividend reinvestment accounts in the plan. Stockholders whose shares are held of record by Cede or by any other depository or nominee on their behalf or their broker-dealers’ behalf will have any shares that they acquire credited to the account of Cede or the other depository or nominee. With respect to all other stockholders, stock certificates for all shares acquired will be mailed after payment for all the shares subscribed for has cleared, which may take up to 15 days from the date of receipt of the payment.

Federal Income Tax Consequences of the Offer

For federal income tax purposes, neither the receipt nor the exercise of the rights by record date stockholders will result in taxable income to such stockholders, and no loss will be realized if the rights expire without exercise.

A record date stockholder’s basis in a right will be zero unless either (1) the fair market value of the right on the date of distribution is 15% or more of the fair market value of the shares with respect to which the right was distributed or (2) the record date stockholder elects, in his or her federal income tax return for the taxable year in which the right is received, to allocate part of the basis of the shares to the right. If either of clauses (1) or (2) is applicable, then if the right is exercised, the record date stockholder will allocate his or her basis in the shares with respect to which the right was distributed between the shares and the right in proportion to the fair market values of each on the date of distribution.

The holding period of a right received by a record date stockholder includes the holding period of the shares with regard to which the right is issued. If the right is exercised, the holding period of the shares acquired begins on the date the right is exercised.

[If a right is sold, a gain or loss will be realized by the rights holder in an amount equal to the difference between the basis of the right sold and the amount realized on its disposition.]

A record date stockholder’s basis for determining gain or loss upon the sale of a share acquired upon the exercise of a right will be equal to the sum of the record date stockholder’s basis in the right, if any, and the subscription price per share. A record date stockholder’s gain or loss recognized upon a sale of a share acquired upon the exercise of a right will be capital gain or loss (assuming the share was held as a capital asset at the time of sale) and will be long-term capital gain or loss if the share is held for more than one year.

The foregoing is a general summary of the material U.S. federal income tax consequences of the offer under the provisions of the Code and Treasury regulations in effect as of the date of the prospectus that are generally applicable to record date stockholders who are United States persons within the meaning of the Code, and does not address any foreign, state or local tax consequences. The Code and Treasury regulations are subject to change or differing interpretations by legislative or administrative action, which may be retroactive. Participating rights holders should consult their tax advisors regarding specific questions as to foreign, federal, state or local taxes.

ERISA Considerations

Stockholders who are employee benefit plans subject to the Employee Retirement Income Security Act of 1974, or ERISA (including corporate savings and 401(k) plans), Keogh or H.R. 10 plans of self-employed individuals and individual retirement accounts should be aware that additional contributions of cash to a retirement plan (other than rollover contributions or trustee-to-trustee transfers from other retirement plans) in order to exercise rights would be treated as contributions to the retirement plan and, when taken together with contributions previously made, may result in, among other things, excise taxes for excess or nondeductible contributions. In the case of retirement plans qualified under Section 401(a) of the Code and certain other retirement plans, additional cash contributions could cause the maximum contribution limitations of Section 415 of the Code or other qualification rules to be violated. It may also be a reportable distribution and there may be other adverse tax and ERISA consequences if rights are sold or transferred by a retirement plan.

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Retirement plans and other tax exempt entities, including governmental plans, should also be aware that if they borrow in order to finance their exercise of rights, they may become subject to the tax on unrelated business taxable income under Section 511 of the Code. If any portion of an individual retirement account is used as security for a loan, the portion so used is also treated as distributed to the IRA depositor. ERISA contains fiduciary responsibility requirements, and ERISA and the Code contain prohibited transaction rules that may impact the exercise of rights. Due to the complexity of these rules and the penalties for noncompliance, retirement plans should consult with their counsel and other advisers regarding the consequences of their exercise of rights under ERISA and the Code.

[Distribution Arrangements

            , which is a broker-dealer and member of the Financial Industry Regulatory Authority, will act as dealer manager for this offer. Under the terms and subject to the conditions contained in the dealer management agreement, the dealer manager will provide financial advisory and marketing services in connection with this offer and will solicit the exercise of rights and participation in the over-subscription privilege. This offer is not contingent upon any number of rights being exercised. We have agreed to pay the dealer manager a fee for its financial advisory, marketing and soliciting services equal to             % of the aggregate subscription price for shares issued pursuant to this offer. In addition, we have agreed to reimburse the dealer manager an aggregate amount up to $             for its expenses incurred in connection with this offer.

The dealer manager will reallow to other broker-dealers that have executed and delivered a soliciting dealer agreement and have solicited the exercise of rights, solicitation fees equal to             % of the subscription price per share for each share issued pursuant to the exercise of rights as a result of their soliciting efforts, subject to a maximum fee based on the number of shares held by each broker-dealer through DTC on the record date. Fees will be paid by us to the broker-dealer designated on the applicable portion of the subscription certificates or, in the absence of such designation, to the dealer manager.

We have agreed to indemnify the dealer manager for, or contribute to losses arising out of, certain liabilities, including liabilities under the Securities Act. The dealer manager agreement also provides that the dealer manager will not be subject to any liability to us in rendering the services contemplated by the dealer manager agreement except for any act of bad faith, willful misfeasance, or gross negligence of the dealer manager or reckless disregard by the dealer manager of its obligations and duties under the dealer manager agreement. We have also agreed not to directly or indirectly sell, offer to sell, enter into any agreement to sell, or otherwise dispose of, any of our equity or equity related securities or securities convertible into such securities, other than the rights, the shares and the common stock issued in connection with the reinvestment of dividends or distributions, for a period of             days from the date hereof without the prior consent of the dealer manager.

The principal business address of the dealer manager is .

Prior to the expiration of this offer, the dealer manager may independently offer for sale shares, including shares acquired through purchasing and exercising the rights, at prices it sets. The dealer manager may realize profits or losses independent of any fees described in this prospectus.

This offering is being conducted in compliance with Rule 5110 of the Conduct Rules of the Financial Industry Regulatory Authority. ]

Additional Dealer Manager Compensation

The dealer manager and/or its affiliates have from time to time performed and may in the future perform various commercial banking, financial advisory and investment banking services for us and our affiliates for which they have received or will receive customary compensation. [Describe any specific transactions and compensation related thereto required to be disclosed by applicable law or regulation.]

Certain Effects of this Offer

As a result of the terms of this offer, stockholders who do not fully exercise their rights will own, upon completion of this offer, a smaller proportional interest in us than they owned prior to the offer, including with respect to voting rights. [In addition, because the subscription price per share will likely be less than the net asset

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value per share, based on our current market price, the offer will likely result in an immediate dilution of net asset value per share for all of our stockholders. If the subscription price per share is substantially less than the current net asset value per share, such dilution could be substantial. Any such dilution will disproportionately affect non-exercising stockholders. If the subscription price is less than our net asset value per share, then all stockholders will experience a decrease in the net asset value per share held by them, irrespective of whether they exercise all or any portion of their rights. This offering will also cause dilution in the dividends per share we are able to distribute subsequent to completion of the offering. See “Dilution.”]

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LEGAL MATTERS

Certain legal matters in connection with the securities offered hereby will be passed upon for us by Sutherland Asbill & Brennan LLP, Washington, DC. Certain legal matters in connection with the securities offered hereby will be passed upon for the underwriters by .

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The consolidated financial statements as of December 31, 20[    ] and 20[    ] and for each of the three years in the period ended December 31, 20[    ] and management’s assessment of the effectiveness of internal control over financial reporting (which is included in Management’s Report on Internal Control over Financial Reporting) as of December 31, 20[    ] included in this prospectus supplement have been so included in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

AVAILABLE INFORMATION

We have filed with the SEC a registration statement on Form N-2, together with all amendments and related exhibits, under the Securities Act, with respect to our shares of common stock offered by this prospectus supplement and the accompanying prospectus. The registration statement contains additional information about us and our shares of common stock being offered by this prospectus supplement and the accompanying prospectus.

We are required to file with or submit to the SEC annual, quarterly and current periodic reports, proxy statements and other information meeting the informational requirements of the Exchange Act. You may inspect and copy these reports, proxy statements and other information, as well as the registration statement and related exhibits and schedules, at the Public Reference Room of the SEC in Washington, D.C. You may obtain information on the operation of the Public Reference Room by calling the SEC at (202) 551-8090. The SEC maintains an Internet site that contains reports, proxy and information statements and other information filed electronically by us with the SEC

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which are available on the SEC’s website at http://www.sec.gov. Copies of these reports, proxy and information statements and other information may be obtained, after paying a duplicating fee, by electronic request at the following e-mail address: publicinfo@sec.gov, or by writing to the SEC’s Public Reference Section, Washington, D.C. 20549. The information is available free of charge by contacting us at Hercules Technology Growth Capital, Inc., 400 Hamilton Avenue, Suite 310, Palo Alto, CA 94301, or by calling us collect at (650) 289-3060 or on our website at www.herculestech.com.

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