Lord Rothschild (pictured) owns 12.4% of the RIT Capital Markets trust, while his charity has a 10% holding.
Fidelity said it had decided to restrict new investment into the fund «in the best interests of our customers».
«You will still be able to redeem existing holdings in the fund either by sell to cash or by switching to other funds,» it added.
RIT Capital Partners chair and third largest shareholder increase stakes amid backlash
RIT Capital Partners has returned -22.2% over the last year, compared to an IT Flexible Investment average of -6.4%, according to data from the Association of Investment Companies.
The trust's discount has also widened, now sitting at 18%. Over the last five years, the trust's share price has grown only 0.3%, while its NAV has risen 33.6%.
In March, Investec described the trust as «uninvestable» due to its lack of transparency and high investment in venture capital.
The trust has a 41% weighting to private markets, with 12% in single unquoted companies and 29% in private equity funds, which Investec described as «ominous».
Investec: Proportion of all-male investment trust boards falls to less than 5%
Investec's analysts said they were worried «specifically [about] the potential for a valuation reset after a tsunami of easy money had driven valuations to nose-bleed levels in 2021», adding that many of the companies it invested in were still «anchored at these last fund-raising rounds».
«This is where we potentially see the greatest source of pain, which is likely to be realised when these companies must come back to investors for more capital,» they said.
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