The fund is still recovering from an 18-percent loss for the year-to-date but the decline is smaller now compared with the end of March when the fund was off 25.6 percent, according to a portfolio update seen by Reuters.

Assets in Ackman's firm, Pershing Square Capital Management, have grown again to stand at $12.4 billion, up from $11.6 billion at the end of March. But they are still below last year's levels which were close to $20 billion.

Ackman ranks as one of the industry's most closely followed investors and his performance has tumbled in the last nine months as Valeant's aggressive accounting practices and sharp price hikes drew scrutiny from lawmakers and investors.

The company has hired a new chief executive and filed its long delayed annual report on Friday, giving its stock price a lift.

(Reporting by Svea Herbst-Bayliss; Editing by Sandra Maler)

By Svea Herbst-Bayliss