FORM OF PROSPECTUS SUPPLEMENT FOR COMMON STOCK OFFERINGS

Exhibit (s)(1)

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 has been declared effective. This preliminary prospectus supplement is not an offer to sell nor does it seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

[FORM OF PROSPECTUS SUPPLEMENT TO BE USED IN

CONJUNCTION WITH FUTURE SECURITIES OFFERINGS]

PROSPECTUS SUPPLEMENT

(to Prospectus dated                 , 2012)

[            ] Shares

Common Stock

We are offering             shares of our common stock. Our common stock is listed on the Nasdaq Global Select Market under the symbol “HTGC.” The last sale price, as reported on NASDAQ on             , was $            per share. The net asset value per share of our common stock at             (the last date prior to the date of this prospectus supplement on which we determined net asset value) was $            .

We are an internally-managed, non-diversified closed-end investment company that has elected to be treated 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.

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 common 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             of the accompanying prospectus and page S- in this prospectus supplement to read about risks that you should consider before investing in our common stock, 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 supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

PRICE $     PER SHARE

The underwriters have an option to purchase up to an additional             shares from us at the public offering price, less the underwriting discounts and commissions, within 30 days from the date of this prospectus supplement to cover overallotments. If the underwriters exercise this option in full, the total public offering price will be $            , the total underwriting discount and commissions (sales load) paid by us will be $            , and total proceeds, before expenses, will be $            .

Delivery of the shares of common stock will be made on or about             , 2012.

The date of this prospectus supplement is             , 2012.

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 common stock.

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

Prospectus Supplement

PROSPECTUS

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.

(1) The underwriting discounts and commissions with respect to the shares sold in this offering, which is a one-time fee, is the only sales load paid in connection with this offering.

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.

PROSPECTUS SUPPLEMENT SUMMARY

Our Company

We are a specialty finance company that provides debt and equity growth capital to technology-related companies at various stages of development from seed and emerging growth to expansion and established stages of development, which include select publicly listed companies and select lower middle market companies. 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 treated as a business development company under the Investment Company Act of 1940, or the 1940 Act.

As of [    ], 20         our total assets were approximately $[    ] million, of which, our investments comprised $[    ] million at fair value and $[    ] million at cost. Our investments at fair value were comprised of our debt investments, warrant portfolio and equity investments valued at approximately $[    ] million, $[    ] million and $[    ] million, respectively, or [    ]%, [    ]% and [    ]% of total investments, respectively. Our[    ], 20         total investments at value in foreign companies were approximately $[    ] million or [    ]% of total assets. During the [    ]-month periods ended [    ], 20        , we made debt commitments totaling $[    ] million and $[    ] million, respectively, and funded approximately $[    ] million and $[    ] million, respectively. During the[    ]-month period ended [    ], 20        , we made and funded equity commitments of approximately $[    ] and $[    ] million to [    ] and[    ] portfolio companies, respectively. Debt commitments for the nine months ended [    ], 20         included commitments of approximately $[    ] million to[    ]new portfolio companies and $[    ] million to [    ] existing portfolio companies. Since inception through [    ], 20        , we have made debt and equity commitments of approximately $[    ] billion to our portfolio companies.

We also make investments in qualifying small businesses through two wholly-owned, small business investment company (“SBIC”) subsidiaries, Hercules Technology II, L.P. (“HT II”) and Hercules Technology III, L.P. (“HT III”). As SBICs, HT II and HT III are subject to a variety of regulations concerning, among other things, the size and nature of the companies in which they may invest and the structure of those investments. As of [    ], 20        , we held investments in HT II in [    ] companies with a fair value of approximately $[    ] million. HT II’s portfolio companies accounted for approximately [    ]% of our total portfolio at [    ], 20        . As of [    ], 20        , we held investments in HT III in [    ] companies with a fair value of approximately $[    ] million. HT III’s portfolio accounted for approximately [    ]% of our total portfolio at [    ], 20        .

In aggregate, HT II and HT III held approximately $[    ] million in assets and accounted for approximately [    ]% of our total assets prior to consolidation at [    ], 20        .

We primarily finance privately-held companies backed by leading venture capital and private equity firms and also may finance certain select publicly-traded companies that lack access to public capital or are sensitive to equity ownership dilution. As of [    ], 20        , our proprietary SQL-based database system included over [    ] technology-related companies and approximately [    ] venture capital, private equity sponsors/investors, as well as various other industry contacts. Our principal executive office is located in Silicon Valley, and we have additional offices in Boston, MA, Boulder, CO and McLean, VA. Our goal is to be the leading structured debt financing provider of choice for venture capital and private equity backed technology-related companies requiring sophisticated and customized financing solutions. Our strategy is to evaluate and invest in a broad range of ventures active in the technology, clean technology and life science industries and to offer a full suite of growth capital products up and down of the capital structure. We invest primarily in structured debt and, to a lesser extent, in senior debt and equity investments. We use the term “structured debt with warrants” to refer to any debt investment, such as a senior or subordinated secured loan, that is coupled with an equity component, including warrants, options or rights to purchase common or preferred stock. Our structured debt with warrants investments will typically be secured by select or all of the assets of the portfolio company.

We focus our investments in companies active in technology industry sub-sectors characterized by products or services that require advanced technologies, including, but not limited to, computer software and hardware, networking systems, semiconductors, semiconductor capital equipment, information technology infrastructure or services, Internet consumer and business services, telecommunications, telecommunications equipment, media and life sciences. Within the life sciences sub-sector, we focus on medical devices, bio-pharmaceutical, drug discovery, drug delivery, health care services and information systems companies. Within the clean technology sub-sector, we

focus on sustainable and renewable energy technologies and energy efficiency and monitoring technologies. We refer to all of these companies as “technology-related” companies and intend, under normal circumstances, to invest at least 80% of the value of our assets in such businesses.

Our primary business objectives are to increase our net income, net operating income and net asset value by investing in structured debt with warrants and equity of venture capital and private equity backed technology-related companies with attractive current yields and the potential for equity appreciation and realized gains. Our structured debt investments typically include warrants or other equity interests, giving us the potential to realize equity-like returns on a portion of our investments. Our equity ownership in our portfolio companies may represent a controlling interest. In some cases, we receive the right to make additional equity investments in our portfolio companies in connection with future equity financing rounds. Capital that we provide directly to venture capital and private equity backed technology-related companies is generally used for growth, and general working capital purposes as well as in select cases for acquisitions or recapitalizations.

Our portfolio is comprised of, and we anticipate that our portfolio will continue to be comprised of, investments in technology-related companies at various stages of development. Consistent with regulatory requirements, we invest primarily in United States based companies and to a lesser extent in foreign companies. See “Regulation—Qualifying Assets” in the accompanying prospectus. Since 2007, our investing emphasis has been primarily on private companies following or in connection with a subsequent institutional round of equity financing, which we refer to as expansion-stage companies and private companies in their later rounds of financing and certain public companies, which we refer to as established-stage companies and lower middle market companies. We have also historically focused our investment activities in private companies following or in connection with the first institutional round of financing, which we refer to as emerging-growth companies.

Beginning in the fall of 2008, the global economy entered a financial crisis and recession. Volatile capital and credit markets, declining business and consumer confidence and increased unemployment precipitated a continuing economic slowdown. Although there have been signs of recovery in many regions, economic weakness could continue or worsen. For example, the current U.S. debt ceiling and budget deficit concerns, together with signs of deteriorating sovereign debt conditions in Europe, have increased the possibility of credit-rating downgrades and economic slowdowns. Although U.S. lawmakers passed legislation to raise the federal debt ceiling, Standard & Poor’s Ratings Services lowered its long-term sovereign credit rating on the United States from “AAA” to “AA+” on August 5, 2011. The impact of this or any further downgrades to the U.S. government’s sovereign credit rating, or its perceived creditworthiness, and the impact of the current crisis in Europe with respect to the ability of certain European Union countries to continue to service their sovereign debt obligations is inherently unpredictable and could adversely effect the U.S. and global financial markets and economic conditions. During market distruptions, we may have difficulty raising debt or equity capital especially as a result of regulatory constraints. There can be no assurance that governmental or other measures to aid economic recovery will be effective.

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.

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:

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, particularly due to the recent credit market dislocation and 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 financial sponsor-backed emerging-growth or expansion-stage companies effectively.

The unique cash flow characteristics of many technology-related companies 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 emerging-growth and expansion-stage 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 mezzanine 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. In the first [    ] months of 20        , venture capital-backed companies received, in approximately [    ] transactions, equity financing in an aggregate amount of approximately $[    ] billion, representing a [    ]% increase from the same period of the preceding year, as reported by Dow Jones VentureSource. In addition, overall, the median round size during the three-month periods ended [    ], 20         and 20         was approximately $[    ] million and $[    ] million, respectively. We believe the larger number of companies provides us a greater opportunity to provide debt financing to these venture backed companies. Overall, seed- and first-round deals made up [    ]% of the deal flow in the three months ended [    ], 20         and later-stage deals made up roughl y[    ]% of the deal activity in the quarter.

We believe that demand for structured debt financing is currently under served, in part because of the credit market collapse in 2008 and the resulting exit of debt capital providers to technology-related companies. 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

sources. Generally, we believe emerging-growth and expansion-stage companies 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 potentially reached a more mature stage prior to reaching a liquidity event, we believe our investments provide the debt capital needed to grow or recapitalize companies 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. Our investment professionals have, on average, more than [    ] years of experience as equity investors in, and/or lenders to, technology-related companies. Our team members have originated structured debt, structured debt with warrants and equity investments in over [    ] technology-related companies, representing over $[    ] billion in commitments from inception through [    ], 20         and have developed a network of industry contacts with investors and other participants within the venture capital and private equity communities. In addition, members of our management team also have operational, research and development and finance experience with technology- related companies. We have established contacts with leading venture capital and private equity fund sponsors, public and private companies, research institutions and other industry participants, which should enable us to identify and attract well-positioned prospective portfolio companies.

We concentrate our investing activities generally in industries in which our investment professionals have investment experience. We believe that our focus on financing technology-related companies will enable us to leverage our expertise in structuring prospective investments, to assess the value of both tangible and intangible assets, to evaluate the business prospects and operating characteristics of technology-related companies and to identify and originate potentially attractive investments with these types of 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 believe that we can mitigate the risk of loss on our debt investments through the combination of loan principal amortization, cash interest payments, relatively short maturities, 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 and the continued support from a venture capital or private equity firm at the time we make our investment.

Historically our structured debt investments to technology-related companies, typically include warrants or other equity interests, giving us the potential to realize equity-like returns on a portion of our investment. In addition, in some cases, we receive the right to make additional equity investments in our portfolio companies in connection with future equity financing rounds. We believe these equity interests will create the potential for meaningful long-term capital gains in connection with the future liquidity events of these technology-related companies.

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. Unlike many of our competitors that only invest in companies that fit a specific set of investment parameters, we have the flexibility to structure our investments to suit the particular needs of our portfolio companies. We offer customized financing solutions ranging from senior debt to equity capital, with a focus on structured debt with warrants.

We use our relationships in the financial sponsor community to originate investment opportunities. Because venture capital and private equity funds typically invest solely in the equity securities of their portfolio companies, we believe that our debt investments will be viewed as an attractive and complementary source of capital, both by the portfolio company and by the portfolio company’s financial sponsor. In addition, we believe that many venture capital and private equity fund sponsors encourage their portfolio companies to use debt financing for a portion of their capital needs as a means of potentially enhancing equity returns, minimizing equity dilution and increasing valuations prior to a subsequent equity financing round or a liquidity event.

Invest at Various Stages of Development. We provide growth capital to technology-related companies at all stages of development, from emerging-growth companies, to expansion-stage companies and established-stage companies, including select publicly listed companies and select lower middle market companies. We believe that this provides us with a broader range of potential investment opportunities than those available to many of our competitors, who generally focus their investments on a particular stage in a company’s development. Because of the flexible structure of our investments and the extensive experience of our investment professionals, we believe we are well positioned to take advantage of these investment opportunities at all stages of prospective portfolio companies’ development.

Benefit from Our Efficient Organizational Structure. We believe that the perpetual nature of our corporate structure enables us to be a long-term partner for our portfolio companies in contrast to traditional mezzanine and 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. We are not subject to requirements to return invested capital to investors nor do we have a finite investment horizon. Capital providers that are subject to such limitations are often required to seek a liquidity event more quickly than they otherwise might, which can result in a lower overall return on an investment.

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. As of [    ], 20        , our proprietary SQL-based database system included over [    ] technology-related companies and over [    ] venture capital, private equity sponsors/investors, as well as various other industry contacts. This proprietary SQL system allows us to maintain, cultivate and grow our industry relationships while providing us with comprehensive details on companies in the technology-related industries and their financial sponsors.

Recent Developments

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

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:

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.

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.

CAPITALIZATION

The following table sets forth (i) our actual capitalization as of             , and (ii) our capitalization as adjusted to reflect the effects of the sale of              shares of our common stock in this offering (assuming no exercise of the underwriters’ overallotment option) at an assumed public offering price of $             per share (based on the last reported sales price of our common stock on                 , 20     ), and after deducting the underwriting discounts and commissions and estimated offering expenses payable by us. You should read this table together with “Use of Proceeds” and our statement of assets and liabilities included elsewhere in this prospectus supplement.

USE OF PROCEEDS

The net proceeds from the sale of             shares of our common stock in this offering will be $             (or $             if the over-allotment is exercised in full) after deducting estimated offering expenses of approximately $             payable by us. A $             increase (decrease) in the assumed offering price per share would increase (decrease) net proceeds to us from this offering by $             million, assuming the number of shares offered by us as set forth on the cover page of this prospectus supplement remains the same. Any additional proceeds to us resulting from an increase in the public offering price or the number of shares offered pursuant to this prospectus supplement will be used by us as described below.

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 anticipate that substantially all of the net proceeds from this offering will be used as described above within twelve months, but in no event longer than two years. Pending such uses and investments, we will invest the net proceeds primarily in cash, cash equivalents, U.S. government securities or high-quality debt securities maturing in one year or less from the time of investment. Our ability to achieve our investment objective may be limited to the extent that the net proceeds of any offering, pending full investment, are held in lower yielding short-term instruments.

UNDERWRITING

are acting as joint bookrunning managers of the offering and as representatives of the underwriters named below. Subject to the terms and conditions stated in the underwriting agreement dated the date of this prospectus supplement, each underwriter named below has agreed to purchase the number of shares set forth opposite the underwriter’s name.

The underwriting agreement provides that the obligations of the underwriters to purchase the shares included in this offering are subject to approval of legal matters by counsel and to other conditions. The underwriters are obligated to purchase all the shares (other than those covered by the over-allotment option described below) if they purchase any of the shares.

The underwriters propose to offer some of the shares directly to the public at the public offering price set forth on the cover page of this prospectus supplement and some of the shares to dealers at the public offering price less a concession not to exceed $             per share. If all of the shares are not sold at the initial offering price, the representatives may change the public offering price and the other selling terms. The representatives have advised us that the underwriters do not intend to confirm sales to discretionary accounts.

We have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase from us up to             additional shares of common stock at the public offering price less the underwriting discount. The underwriters may exercise the option solely for the purpose of covering over-allotments, if any, in connection with this offering. To the extent the option is exercised, each underwriter must purchase a number of additional shares approximately proportionate to that underwriter’s initial purchase commitment.

We, our officers and directors have agreed with the underwriters, subject to certain exceptions, not to issue, sell, dispose of or hedge any of our common stock or securities convertible into or exchangeable for shares of common stock during the period from the date of this prospectus supplement continuing through the date days after the date of this prospectus supplement, except with the prior written consent of .

The     -day restricted period described in the preceding paragraph will be automatically extended if: (1) during the last 17 days of the     -day restricted period we issue an earnings release or announce material news or a material event; or (2) prior to the expiration of the     -day restricted period, we announce that we will release earnings results during the 15-day period following the last day of the     -day period, in which case the restrictions described in the preceding paragraph will continue to apply until the expiration of the 18-day period beginning on the issuance of the earnings release of the announcement of the material news or material event.

Our common stock is listed on the Nasdaq Global Select Market under the symbol “HTGC”.

The following table shows the underwriting discounts and commissions that we are to pay to the underwriters in connection with this offering. These amounts are shown assuming both no exercise and full

exercise of the underwriters’ option to purchase from us additional shares of common stock. This offering will conform with the requirements set forth in Financial Industry Regulatory Authority Rule 2310. In compliance with such requirements, the underwriting discounts and commissions in connection with the sale of securities will not exceed 8% of gross proceeds of this offering.

In connection with the offering, one or more of the underwriters may purchase and sell shares of common stock in the open market. These transactions may include short sales, syndicate covering transactions and stabilizing transactions. Short sales involve syndicate sales of common stock in excess of the number of shares to be purchased by the underwriters in the offering, which creates a syndicate short position. “Covered” short sales are sales of shares made in an amount up to the number of shares represented by the underwriters’ over-allotment option. In determining the source of shares to close out the covered syndicate short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the over-allotment option. Transactions to close out the covered syndicate short involve either purchases of the common stock in the open market after the distribution has been completed or the exercise of the over-allotment option. The underwriters may also make “naked” short sales of shares in excess of the over-allotment option. The underwriters must close out any naked short position by purchasing shares of common stock in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the shares in the open market after pricing that could adversely affect investors who purchase in the offering. Stabilizing transactions consist of bids for or purchases of shares in the open market while the offering is in progress.

The underwriters may also impose a penalty bid. Penalty bids permit the underwriters to reclaim a selling concession from a syndicate member when the representatives repurchase shares originally sold by that syndicate member in order to cover syndicate short positions or make stabilizing purchases.

Any of these activities may have the effect of preventing or retarding a decline in the market price of the common stock. They may also cause the price of the common stock to be higher than the price that would otherwise exist in the open market in the absence of these transactions. The underwriters may conduct these transactions on the Nasdaq Global Select Market or in the over-the-counter market, or otherwise. If the underwriters commence any of these transactions, they may discontinue them at any time.

We estimate that our portion of the total expenses of this offering will be $            .

The underwriters have performed investment banking and advisory services for us and our affiliates from time to time for which they have received customary fees and expenses. The underwriters may, from time to time, engage in transactions with and perform services for us and our affiliates in the ordinary course of their business. Each of the underwriters acted as underwriters in our initial public offering.

This prospectus supplement and the accompanying prospectus in electronic format may be made available on the websites maintained by one or more of the underwriters. Other than the prospectus supplement and the accompanying prospectus in electronic format, the information on any such underwriter’s website is not part of this prospectus supplement and the accompanying prospectus. The representatives may agree to allocate a number of shares to underwriters for sale to their online brokerage account holders. The representatives will allocate shares to underwriters that may make Internet distributions on the same basis as other allocations. In addition, shares may be sold by the underwriters to securities dealers who resell shares to online brokerage account holders.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the underwriters may be required to make because of any of those liabilities.

In the ordinary course of their various business activities, the underwriters and their respective affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers and may at any time hold long and short positions in such securities and instruments. Such investment and securities activities may involve securities and instruments of ours.

The principal business address of             is             ,             ,             .

LEGAL MATTERS

Certain legal matters with respect to the validity of the shares of common stock we are offering will be passed upon for us by Sutherland Asbill & Brennan LLP, Washington, D.C. Certain legal matters related to the offering will be passed upon for the underwriters by .

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The financial statements as of                 , 20     and for the year ended December 31, 20    , included in this prospectus, and the effectiveness of internal control over financial reporting as of December 31, 20     have been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report appearing herein.

Certain of our audited consolidated financial statements included in this prospectus have been so included in reliance upon the report of Ernst & Young LLP, our former independent registered public accountants. Ernst & Young LLP’s principal business address is 560 Mission Street, San Francisco, CA 94105.

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. The registration statement contains additional information about us and our shares of common stock being offered by this prospectus supplement.

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 http://www.sec.gov, that contains reports, proxy and information statements, and other information regarding issuers, including us, who file documents electronically with the SEC.