Neil Woodford's £752m Patient Capital Trust is seeking to remove a number of restrictions currently imposed on the vehicle in a bid to allow greater investment flexibility.
As part of the proposed changes, the trust would amend its remit to allow its maximum exposure to unquoted companies to rise from 60 per cent to 80 per cent.
A limit on the trust's weighting to non-UK companies would also be removed. Meanwhile the trust would remove reference to "early-growth" companies, which are typically quoted, in its list of investments.
In an update, the trust's chairman Susan Searle said that the changes could help to avoid opportunities becoming more limited in future.
"In light of the progress being made across much of the portfolio, Woodford has undertaken an analysis of how the shape of the portfolio may change over time, as material success on a stock-specific basis emerges," she said.
"This analysis has highlighted a rationale for amending some of the portfolio's investment restrictions, in order to make the most of investment opportunities and avoid constraints in the future."
The board added that such amendments would give the fund "greater flexibility to capture growth and follow-on investment opportunities".
While popular, the trust has struggled since launch. According to FE Analytics it has shed 8 per cent over one year, compared with an average 18.1 per cent return from its AIC UK All Companies peer group.