N-2	12 Months Ended
Dec. 31, 2023
Cover [Abstract]
Entity Central Index Key	0000919567
Amendment Flag	false
Entity Inv Company Type	N-2
Document Type	N-CSR
Entity Registrant Name	RENN Fund, Inc.
General Description of Registrant [Abstract]
Risk Factors [Table Text Block]	Note 3 – Principal Investment Risks Investing in common stocks and other equity or equity-related securities has inherent risks that could cause you to lose money. Some of the principal risks of investing in the Fund are listed below and could adversely affect the net asset value (“NAV”), total return and value of the Fund and your investment. These are not the only risks associated with an investment in the Fund. Rather, the risks discussed below are certain of the significant risks associated with the investment strategy employed by the Fund. The below does not discuss numerous other risks associated with an investment in the Fund, including risks associated with investments in non-diversified, closed-end registered investment funds generally, other business, operating and tax risks associated with an investment in the Fund, and economic and other risks affecting investment markets generally, all of which are beyond the scope of this discussion. Liquidity Risks: The Investment Advisor may not be able to sell portfolio securities at an optimal time or price. For example, if the Fund is required or the advisor deems it advisable to liquidate all or a portion of a portfolio security quickly, it may realize significantly less than the value at which the investment was previously recorded. Private Issuer Risks: In addition to the risks associated with small public companies, limited or no public information may exist about private companies, and the Fund will rely on the ability of our Investment Advisor to obtain adequate information to evaluate the potential returns from investing in these companies. If the Investment Advisor is unable to uncover all material information about these companies, the Fund may not make a fully informed investment decision and may lose money on the investment. Interest Rate Risk: When interest rates increase, any fixed-income securities held by the Fund may decline in value. Long-term fixed-income securities will normally have more price volatility because of this risk than short-term fixed-income securities. The negative impact on fixed-income securities from the resulting rate increases for that and other reasons could be swift and significant. Leveraging Risks: Investments in derivative instruments may give rise to a form of leverage. The Investment Advisor may engage in speculative transactions which involve substantial risk and leverage. The use of leverage by the Investment Advisor may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s NAV or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions. Distressed Debt Risks: An investment in distressed debt involves considerable risks, including a higher risk of nonpayment by the debtor. The Fund may incur significant expenses seeking recovery upon default or attempting to negotiate new terms. Furthermore, if one of our portfolio companies were to file for bankruptcy protection, a bankruptcy court might re-characterize the debt held by the Fund and subordinate all or a portion of the Fund’s claim to claims of other creditors, even, in some cases, if the investment is structured as senior secured debt. The bankruptcy process has a number of significant inherent risks, including substantial delays and the risk of loss of all or a substantial portion of the Fund’s investment in the bankrupt entity. Bitcoin Risk: The value of the Fund’s investment in the Grayscale Bitcoin Trust is subject directly to fluctuations in the value of bitcoins. The value of bitcoins is determined by the supply of and demand for bitcoins in the global market for the trading of bitcoins, which consists of transactions on electronic bitcoin exchanges (“Bitcoin Exchanges”). Pricing on Bitcoin Exchanges and other venues can be volatile and can adversely affect the value of the Grayscale Bitcoin Trust. Currently, there is relatively small use of bitcoins in the retail and commercial marketplace in comparison to the relatively large use of bitcoins by speculators, thus contributing to price volatility that could adversely affect the Fund’s direct investment in the Grayscale Bitcoin Trust. Bitcoin transactions are irrevocable, and stolen or incorrectly transferred bitcoins may be irretrievable. As a result, any incorrectly executed bitcoin transactions could adversely affect the value of the Fund’s direct or indirect investment in the Grayscale Bitcoin Trust. Shares of the Grayscale Bitcoin Trust may trade at a premium or discount to the net asset value of the Grayscale Bitcoin Trust. Short-Selling Risk: The Fund can sell securities short to the maximum extent permitted under the Investment Company Act of 1940 (the “1940 Act”). A short sale by the Fund involves borrowing a security from a lender which is then sold in the open market. At a future date, the security is repurchased by the Fund and returned to the lender. While the security is borrowed, the proceeds from the sale are deposited with the lender and the Fund may be required to pay interest and/or the equivalent of any dividend payments paid by the security to the lender. If the value of the security declines between the time the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund makes a profit on the difference (less any expenses the Fund is required to pay the lender). There is no assurance that a security will decline in value during the period of the short sale and make a profit for the Fund. If the value of the security sold short increases between the time that the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund will realize a loss on the difference (plus any expenses the Fund is required to pay to the lender). This loss is theoretically unlimited as there is no limit as to how high the security sold short can appreciate in value, thus increasing the cost of buying that security to cover a short position. The Fund may incur interest or other expenses in selling securities short and such expenses are investment expenses of the Fund. Investments in Leveraged/Inverse ETFs and ETNs: The Fund may invest long or short in leveraged/inverse ETFs and ETNs. Leveraged/inverse ETFs and ETNs are designed for investors who seek leveraged long or leveraged inverse exposure, as applicable, to the daily performance of an index. These instruments do not guarantee any return of principal and do not pay any interest during their term. In general, investors will be entitled to receive a cash payment, upon early redemption or upon acceleration, as applicable, that will be linked to the performance of an underlying index, plus a daily accrual and less a daily investor fee. Investors should be willing to forgo interest payments and, if the index on which the ETF or ETN is based declines or increases, as applicable, be willing to lose up to 100% of their investment. In many instances a leveraged or inverse ETF or ETN will seek to provide an investor with a corresponding multiple of the index it tracks (e.g., a three times leveraged long ETF that tracks the S&P 500 Index seeks to provide investors with three times the positive rate of return of the S&P 500 Index on a daily basis). Such ETFs and ETNs are very sensitive to changes in the level of their corresponding index, and returns may be negatively impacted in complex ways by the volatility of the corresponding index on a daily or intraday basis.
Liquidity Risks
General Description of Registrant [Abstract]
Risk [Text Block]	Liquidity Risks: The Investment Advisor may not be able to sell portfolio securities at an optimal time or price. For example, if the Fund is required or the advisor deems it advisable to liquidate all or a portion of a portfolio security quickly, it may realize significantly less than the value at which the investment was previously recorded.
Private Issuer Risks
General Description of Registrant [Abstract]
Risk [Text Block]	Private Issuer Risks: In addition to the risks associated with small public companies, limited or no public information may exist about private companies, and the Fund will rely on the ability of our Investment Advisor to obtain adequate information to evaluate the potential returns from investing in these companies. If the Investment Advisor is unable to uncover all material information about these companies, the Fund may not make a fully informed investment decision and may lose money on the investment.
Interest Rate Risk [Member]
General Description of Registrant [Abstract]
Risk [Text Block]	Interest Rate Risk: When interest rates increase, any fixed-income securities held by the Fund may decline in value. Long-term fixed-income securities will normally have more price volatility because of this risk than short-term fixed-income securities. The negative impact on fixed-income securities from the resulting rate increases for that and other reasons could be swift and significant.
Leveraging Risks
General Description of Registrant [Abstract]
Risk [Text Block]	Leveraging Risks: Investments in derivative instruments may give rise to a form of leverage. The Investment Advisor may engage in speculative transactions which involve substantial risk and leverage. The use of leverage by the Investment Advisor may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s NAV or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.
Distressed Debt Risks
General Description of Registrant [Abstract]
Risk [Text Block]	Distressed Debt Risks: An investment in distressed debt involves considerable risks, including a higher risk of nonpayment by the debtor. The Fund may incur significant expenses seeking recovery upon default or attempting to negotiate new terms. Furthermore, if one of our portfolio companies were to file for bankruptcy protection, a bankruptcy court might re-characterize the debt held by the Fund and subordinate all or a portion of the Fund’s claim to claims of other creditors, even, in some cases, if the investment is structured as senior secured debt. The bankruptcy process has a number of significant inherent risks, including substantial delays and the risk of loss of all or a substantial portion of the Fund’s investment in the bankrupt entity.
Bitcoin Risk
General Description of Registrant [Abstract]
Risk [Text Block]	Bitcoin Risk: The value of the Fund’s investment in the Grayscale Bitcoin Trust is subject directly to fluctuations in the value of bitcoins. The value of bitcoins is determined by the supply of and demand for bitcoins in the global market for the trading of bitcoins, which consists of transactions on electronic bitcoin exchanges (“Bitcoin Exchanges”). Pricing on Bitcoin Exchanges and other venues can be volatile and can adversely affect the value of the Grayscale Bitcoin Trust. Currently, there is relatively small use of bitcoins in the retail and commercial marketplace in comparison to the relatively large use of bitcoins by speculators, thus contributing to price volatility that could adversely affect the Fund’s direct investment in the Grayscale Bitcoin Trust. Bitcoin transactions are irrevocable, and stolen or incorrectly transferred bitcoins may be irretrievable. As a result, any incorrectly executed bitcoin transactions could adversely affect the value of the Fund’s direct or indirect investment in the Grayscale Bitcoin Trust. Shares of the Grayscale Bitcoin Trust may trade at a premium or discount to the net asset value of the Grayscale Bitcoin Trust.
Short-Selling Risk
General Description of Registrant [Abstract]
Risk [Text Block]	Short-Selling Risk: The Fund can sell securities short to the maximum extent permitted under the Investment Company Act of 1940 (the “1940 Act”). A short sale by the Fund involves borrowing a security from a lender which is then sold in the open market. At a future date, the security is repurchased by the Fund and returned to the lender. While the security is borrowed, the proceeds from the sale are deposited with the lender and the Fund may be required to pay interest and/or the equivalent of any dividend payments paid by the security to the lender. If the value of the security declines between the time the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund makes a profit on the difference (less any expenses the Fund is required to pay the lender). There is no assurance that a security will decline in value during the period of the short sale and make a profit for the Fund. If the value of the security sold short increases between the time that the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund will realize a loss on the difference (plus any expenses the Fund is required to pay to the lender). This loss is theoretically unlimited as there is no limit as to how high the security sold short can appreciate in value, thus increasing the cost of buying that security to cover a short position. The Fund may incur interest or other expenses in selling securities short and such expenses are investment expenses of the Fund.
Investments in Leveraged/Inverse ETFs and ETNs
General Description of Registrant [Abstract]
Risk [Text Block]	Investments in Leveraged/Inverse ETFs and ETNs: The Fund may invest long or short in leveraged/inverse ETFs and ETNs. Leveraged/inverse ETFs and ETNs are designed for investors who seek leveraged long or leveraged inverse exposure, as applicable, to the daily performance of an index. These instruments do not guarantee any return of principal and do not pay any interest during their term. In general, investors will be entitled to receive a cash payment, upon early redemption or upon acceleration, as applicable, that will be linked to the performance of an underlying index, plus a daily accrual and less a daily investor fee. Investors should be willing to forgo interest payments and, if the index on which the ETF or ETN is based declines or increases, as applicable, be willing to lose up to 100% of their investment. In many instances a leveraged or inverse ETF or ETN will seek to provide an investor with a corresponding multiple of the index it tracks (e.g., a three times leveraged long ETF that tracks the S&P 500 Index seeks to provide investors with three times the positive rate of return of the S&P 500 Index on a daily basis). Such ETFs and ETNs are very sensitive to changes in the level of their corresponding index, and returns may be negatively impacted in complex ways by the volatility of the corresponding index on a daily or intraday basis.

0000919567

N-2

RENN Fund, Inc.

Note 3 – Principal Investment Risks

Investing in common stocks and other equity or equity-related securities has inherent risks that could cause you to lose money. Some of the principal risks of investing in the Fund are listed below and could adversely affect the net asset value (“NAV”), total return and value of the Fund and your investment. These are not the only risks associated with an investment in the Fund. Rather, the risks discussed below are certain of the significant risks associated with the investment strategy employed by the Fund. The below does not discuss numerous other risks associated with an investment in the Fund, including risks associated with investments in non-diversified, closed-end registered investment funds generally, other business, operating and tax risks associated with an investment in the Fund, and economic and other risks affecting investment markets generally, all of which are beyond the scope of this discussion.

Liquidity Risks: The Investment Advisor may not be able to sell portfolio securities at an optimal time or price. For example, if the Fund is required or the advisor deems it advisable to liquidate all or a portion of a portfolio security quickly, it may realize significantly less than the value at which the investment was previously recorded.

Private Issuer Risks: In addition to the risks associated with small public companies, limited or no public information may exist about private companies, and the Fund will rely on the ability of our Investment Advisor to obtain adequate information to evaluate the potential returns from investing in these companies. If the Investment Advisor is unable to uncover all material information about these companies, the Fund may not make a fully informed investment decision and may lose money on the investment.

Interest Rate Risk: When interest rates increase, any fixed-income securities held by the Fund may decline in value. Long-term fixed-income securities will normally have more price volatility because of this risk than short-term fixed-income securities. The negative impact on fixed-income securities from the resulting rate increases for that and other reasons could be swift and significant.

Leveraging Risks: Investments in derivative instruments may give rise to a form of leverage. The Investment Advisor may engage in speculative transactions which involve substantial risk and leverage. The use of leverage by the Investment Advisor may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s NAV or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

Distressed Debt Risks: An investment in distressed debt involves considerable risks, including a higher risk of nonpayment by the debtor. The Fund may incur significant expenses seeking recovery upon default or attempting to negotiate new terms. Furthermore, if one of our portfolio companies were to file for bankruptcy protection, a bankruptcy court might re-characterize the debt held by the Fund and subordinate all or a portion of the Fund’s claim to claims of other creditors, even, in some cases, if the investment is structured as senior secured debt. The bankruptcy process has a number of significant inherent risks, including substantial delays and the risk of loss of all or a substantial portion of the Fund’s investment in the bankrupt entity.

Bitcoin Risk: The value of the Fund’s investment in the Grayscale Bitcoin Trust is subject directly to fluctuations in the value of bitcoins. The value of bitcoins is determined by the supply of and demand for bitcoins in the global market for the trading of bitcoins, which consists of transactions on electronic bitcoin exchanges (“Bitcoin Exchanges”). Pricing on Bitcoin Exchanges and other venues can be volatile and can adversely affect the value of the Grayscale Bitcoin Trust. Currently, there is relatively small use of bitcoins in the retail and commercial marketplace in comparison to the relatively large use of bitcoins by speculators, thus contributing to price volatility

that could adversely affect the Fund’s direct investment in the Grayscale Bitcoin Trust. Bitcoin transactions are irrevocable, and stolen or incorrectly transferred bitcoins may be irretrievable. As a result, any incorrectly executed bitcoin transactions could adversely affect the value of the Fund’s direct or indirect investment in the Grayscale Bitcoin Trust. Shares of the Grayscale Bitcoin Trust may trade at a premium or discount to the net asset value of the Grayscale Bitcoin Trust.

Short-Selling Risk: The Fund can sell securities short to the maximum extent permitted under the Investment Company Act of 1940 (the “1940 Act”). A short sale by the Fund involves borrowing a security from a lender which is then sold in the open market. At a future date, the security is repurchased by the Fund and returned to the lender. While the security is borrowed, the proceeds from the sale are deposited with the lender and the Fund may be required to pay interest and/or the equivalent of any dividend payments paid by the security to the lender. If the value of the security declines between the time the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund makes a profit on the difference (less any expenses the Fund is required to pay the lender). There is no assurance that a security will decline in value during the period of the short sale and make a profit for the Fund. If the value of the security sold short increases between the time that the Fund borrows the security and the time it repurchases and returns the security to the lender, the Fund will realize a loss on the difference (plus any expenses the Fund is required to pay to the lender). This loss is theoretically unlimited as there is no limit as to how high the security sold short can appreciate in value, thus increasing the cost of buying that security to cover a short position. The Fund may incur interest or other expenses in selling securities short and such expenses are investment expenses of the Fund.

Investments in Leveraged/Inverse ETFs and ETNs: The Fund may invest long or short in leveraged/inverse ETFs and ETNs. Leveraged/inverse ETFs and ETNs are designed for investors who seek leveraged long or leveraged inverse exposure, as applicable, to the daily performance of an index. These instruments do not guarantee any return of principal and do not pay any interest during their term. In general, investors will be entitled to receive a cash payment, upon early redemption or upon acceleration, as applicable, that will be linked to the performance of an underlying index, plus a daily accrual and less a daily investor fee. Investors should be willing to forgo interest payments and, if the index on which the ETF or ETN is based declines or increases, as applicable, be willing to lose up to 100% of their investment. In many instances a leveraged or inverse ETF or ETN will seek to provide an investor with a corresponding multiple of the index it tracks (e.g., a three times leveraged long ETF that tracks the S&P 500 Index seeks to provide investors with three times the positive rate of return of the S&P 500 Index on a daily basis). Such ETFs and ETNs are very sensitive to changes in the level of their corresponding index, and returns may be negatively impacted in complex ways by the volatility of the corresponding index on a daily or intraday basis.

General Description of Registrant [Abstract]

Risk [Text Block]

Private Issuer Risks: In addition to the risks associated with small public companies, limited or no public information may exist about private companies, and the Fund will rely on the ability of our Investment Advisor to obtain adequate information to evaluate the potential returns from investing in these companies. If the Investment Advisor is unable to uncover all material information about these companies, the Fund may not make a fully informed investment decision and may lose money on the investment.

General Description of Registrant [Abstract]

Risk [Text Block]

Leveraging Risks: Investments in derivative instruments may give rise to a form of leverage. The Investment Advisor may engage in speculative transactions which involve substantial risk and leverage. The use of leverage by the Investment Advisor may increase the volatility of the Fund. These leveraged instruments may result in losses to the Fund or may adversely affect the Fund’s NAV or total return, because instruments that contain leverage are more sensitive to changes in interest rates. The Fund may also have to sell assets at inopportune times to satisfy its obligations in connection with such transactions.

General Description of Registrant [Abstract]

Risk [Text Block]

Bitcoin Risk: The value of the Fund’s investment in the Grayscale Bitcoin Trust is subject directly to fluctuations in the value of bitcoins. The value of bitcoins is determined by the supply of and demand for bitcoins in the global market for the trading of bitcoins, which consists of transactions on electronic bitcoin exchanges (“Bitcoin Exchanges”). Pricing on Bitcoin Exchanges and other venues can be volatile and can adversely affect the value of the Grayscale Bitcoin Trust. Currently, there is relatively small use of bitcoins in the retail and commercial marketplace in comparison to the relatively large use of bitcoins by speculators, thus contributing to price volatility

that could adversely affect the Fund’s direct investment in the Grayscale Bitcoin Trust. Bitcoin transactions are irrevocable, and stolen or incorrectly transferred bitcoins may be irretrievable. As a result, any incorrectly executed bitcoin transactions could adversely affect the value of the Fund’s direct or indirect investment in the Grayscale Bitcoin Trust. Shares of the Grayscale Bitcoin Trust may trade at a premium or discount to the net asset value of the Grayscale Bitcoin Trust.

General Description of Registrant [Abstract]

Risk [Text Block]

Investments in Leveraged/Inverse ETFs and ETNs: The Fund may invest long or short in leveraged/inverse ETFs and ETNs. Leveraged/inverse ETFs and ETNs are designed for investors who seek leveraged long or leveraged inverse exposure, as applicable, to the daily performance of an index. These instruments do not guarantee any return of principal and do not pay any interest during their term. In general, investors will be entitled to receive a cash payment, upon early redemption or upon acceleration, as applicable, that will be linked to the performance of an underlying index, plus a daily accrual and less a daily investor fee. Investors should be willing to forgo interest payments and, if the index on which the ETF or ETN is based declines or increases, as applicable, be willing to lose up to 100% of their investment. In many instances a leveraged or inverse ETF or ETN will seek to provide an investor with a corresponding multiple of the index it tracks (e.g., a three times leveraged long ETF that tracks the S&P 500 Index seeks to provide investors with three times the positive rate of return of the S&P 500 Index on a daily basis). Such ETFs and ETNs are very sensitive to changes in the level of their corresponding index, and returns may be negatively impacted in complex ways by the volatility of the corresponding index on a daily or intraday basis.