Keith Meister's Corvex Capital has taken a large take in Yum Brands, sources told CNBC.
Corvex is now one of Yum's top five shareholders, purchasing shares early in the first quarter of 2015, according to sources. Meister will offer more details about his investment on Monday at the IRA Sohn Conference.
Meister bought Yum stake earlier in the first quarter, according to the sources.
Shares held their sharp gains.
While Loeb is bullish on the U.S., he noted that Third Point had "invested in more single name shorts this year than in all of 2014 combined," the letter said, referring to bets he made against some companies.
The letter said the firm was "constructive" on the U.S. because of improving economic data and the likelihood of continued low interest rates.
"These factors should create an environment where growth improves and monetary policy stays flexible, which is generally good for equities (higher multiples notwithstanding)," the letter said. "We may follow last year's playbook and ignore the old adage to 'sell in May and go away.'"
A spokesman for Third Point declined to comment. The firm manages about $17.5 billion. Its main fund is up 3.8 percent net of fees through April, according to performance information obtained by CNBC.