The fund formerly run by under-fire manager Neil Woodford has slashed the value of its stake in a Brad Pitt-backed nuclear energy company.
Woodford Patient Capital Trust, which is under new management, cut the valuation of its holding in Industrial Heat, an unproved cold fusion venture, by £45 million.
Alongside the 5p-per-share writedown, the fund announced a 0.7p increase in how it values another unnamed investment. Taken together this means a net loss of £39 million for the fund.
It is the second time that Mr Woodford’s former fund has written down Industrial Heat, which plans to develop a controversial and unproven nuclear technology.
Cold fusion would theoretically revolutionise energy production, producing nuclear power without heat waste. However, many scientists are skeptical that the technology can be developed.
The fund took a £30 million writedown, or 3.7p per share, on the company in August this year.
The Woodford funds own around a quarter of Industrial Heat, which was once valued at nearly 1 billion dollars (£774 million).
Other investors include actor Pitt, and the widow of former Apple boss Steve Jobs, Laurene Powell Jobs.
The company has raised around 100 million dollars (£77 million) to develop cold fusion.
Once run by City superstar Neil Woodford, Woodford Patient Capital Trust was renamed Schroder UK Public Private Trust after its new managers when Mr Woodford stepped down.
Questions were raised over its future when a sister fund was forced to ban investors from withdrawing their money in June.
Mr Woodford had been criticised for locking too much money into illiquid investments which could not be exchanged for cash quickly.
This meant the fund was unable to honour investors’ requests to give their money back in time.