Maine Public Employees Retirement System is planning to invest 20% of its real estate allocation in Blackstone’s US core-plus fund.

The pension fund confirmed to IPE Real Estate that it had approved its biggest-ever commitment to a real estate fund, pledging $350m (€319m) to the open-ended Blackstone Property Partners.

Blackstone did not comment.

Previously, the pension fund’s largest commitments were $150m to the Invesco US Income Fund in 2014 and $150m to Stockbridge Capital’s Smart Markets Fund in 2013, according to the pension fund’s website.

The Blackstone commitment, which is still to go through final due diligence and negotiations, would mean that Maine PERS holds one fifth of its $1.75bn real estate portfolio in a single commitment.

Blackstone Property Partners has a total net asset value of $13.3bn, according to Blackstone’s first-quarter earnings report for 2017. The fund’s net internal rate of return is 13%.

Real estate represents 10.1% of total assets of Maine PERS, just above its 10% target allocation.

Maine PERS told IPE Real Estate it is planning to rebalance its real estate portfolio by reallocating capital between fund managers.

It has holdings in closed-ended and open-ended real estate funds, including PRISA, JP Morgan Strategic Property Fund and the Principal US Property Account.