One of the most successful partnerships in hedge fund history is coming to an end with the departure of James Pallotta from Tudor Investment Corp.

The well-known stock-picker is leaving the Connecticut hedge fund giant, which has $18 billion in assets under management, to form his own firm, as he is taking the money he manages with him, according to a letter to investors.

The Wall Street Journal reports that the Aug. 6 letter told clients that Pallotta’s $5 billion Raptor Global Fund and his Altar Rock funds will join him at the new firm. He will also continue to invest for Tudor’s flagship BVI Global Fund.

Pallotta’s new firm—it is unclear what it will be called—will debut next year. Clients were told that more information “on Jim’s new business and on operational aspects of the transition” would come “as decisions are made and as more details are available.”

The letter added that the 15-year Tudor veteran may expand into private equity at his new firm.