Activist investor Bill Ackman is cutting 10 employees after assets overseen by his hedge fund firm shrank, according to a person with knowledge of the matter.

With Pershing Square Capital Management now overseeing about US$9 billion -- less than half the assets it had at its 2015 peak -- the firm decided to reduce support staff, said the person, who asked not to be named because the matter is private. One investment professional is also among those being laid off, said the person. Reuters reported the job cuts earlier Monday.

A representative for the New York-based firm declined to comment.

Pershing Square is also planning to free up Ackman to focus more fully on money management by having partner Ben Hakim interface with investors, said the person. The firm’s private funds fell as much as 3.2 per cent last year, while the average activist hedge fund gained 4.7 per cent, according to Hedge Fund Research Inc.