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    <dei:SecurityExchangeName contextRef="c-2" id="f-20">NYSE</dei:SecurityExchangeName>
    <dei:Security12bTitle contextRef="c-3" id="f-21">6.25% Notes due 2033</dei:Security12bTitle>
    <dei:TradingSymbol contextRef="c-3" id="f-22">HCXY</dei:TradingSymbol>
    <dei:SecurityExchangeName contextRef="c-3" id="f-23">NYSE</dei:SecurityExchangeName>
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    <cef:LongTermDebtTableTextBlock contextRef="c-1" id="f-27">&lt;div style="margin-bottom:12pt"&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;On October 8, 2026, in connection with a previously announced public offering, Hercules Capital, Inc. (the &#x201c;&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:700;line-height:139%"&gt;Company&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;&#x201d;) and U.S. Bank Trust Company, National Association, as trustee (the &#x201c;&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:700;line-height:139%"&gt;Trustee&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;&#x201d;), entered into the Twelfth Supplemental Indenture (the &#x201c;&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:700;line-height:139%"&gt;Twelfth Supplemental Indenture&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;&#x201d;) to that certain indenture, dated March 6, 2012, between the Company and the Trustee (together with the Twelfth Supplemental Indenture, the &#x201c;&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:700;line-height:139%"&gt;Indenture&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;&#x201d;). The Twelfth Supplemental Indenture relates to the Company&#x2019;s issuance, offer and sale of $400,000,000 in aggregate principal amount of its 6.700% Notes due 2029 (the &#x201c;&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-style:italic;font-weight:700;line-height:139%"&gt;Notes&lt;/span&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;&#x201d;).&lt;/span&gt;&lt;/div&gt;&lt;div style="margin-bottom:12pt"&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;The Notes will mature on October 8, 2029, unless previously redeemed or repurchased in accordance with their terms. The interest rate of the Notes is 6.700% per year and will be paid semiannually in arrears on April 8 and October 8 of each year, commencing April 8, 2027. The Notes are the Company&#x2019;s unsecured obligations that rank senior in right of payment to all of the Company&#x2019;s existing and future indebtedness that is expressly subordinated, or junior, in right of payment to the Notes. The Notes will not be guaranteed by any of the Company&#x2019;s current or future subsidiaries. The Notes will rank pari passu, or equally, in right of payment with all of the Company&#x2019;s existing and future liabilities that are not so subordinated, or junior. The Notes will effectively rank subordinated, or junior, to any of the Company&#x2019;s secured indebtedness (including unsecured indebtedness that the Company later secures) to the extent of the value of the assets securing such indebtedness. The Notes will rank structurally subordinated, or junior, to all existing and future indebtedness (including trade payables) incurred by the Company&#x2019;s subsidiaries, financing vehicles or similar facilities.&lt;/span&gt;&lt;/div&gt;&lt;div style="margin-bottom:12pt"&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;The Notes may be redeemed in whole or in part at any time or from time to time at the Company&#x2019;s option at par, plus a &#x201c;make whole&#x201d; premium, if applicable.&lt;/span&gt;&lt;/div&gt;</cef:LongTermDebtTableTextBlock>
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    <cef:LongTermDebtStructuringTextBlock contextRef="c-1" id="f-29">&lt;div style="margin-bottom:12pt"&gt;&lt;span style="color:#000000;font-family:'Times New Roman',serif;font-size:10pt;font-weight:400;line-height:139%"&gt;The Notes will mature on October 8, 2029, unless previously redeemed or repurchased in accordance with their terms. The interest rate of the Notes is 6.700% per year and will be paid semiannually in arrears on April 8 and October 8 of each year, commencing April 8, 2027. The Notes are the Company&#x2019;s unsecured obligations that rank senior in right of payment to all of the Company&#x2019;s existing and future indebtedness that is expressly subordinated, or junior, in right of payment to the Notes. The Notes will not be guaranteed by any of the Company&#x2019;s current or future subsidiaries. The Notes will rank pari passu, or equally, in right of payment with all of the Company&#x2019;s existing and future liabilities that are not so subordinated, or junior. The Notes will effectively rank subordinated, or junior, to any of the Company&#x2019;s secured indebtedness (including unsecured indebtedness that the Company later secures) to the extent of the value of the assets securing such indebtedness. The Notes will rank structurally subordinated, or junior, to all existing and future indebtedness (including trade payables) incurred by the Company&#x2019;s subsidiaries, financing vehicles or similar facilities.&lt;/span&gt;&lt;/div&gt;</cef:LongTermDebtStructuringTextBlock>
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