UnitedHealth Group ($UNH) stock rallied about 12% on Friday, as Warren Buffett’s Berkshire Hathaway (BRK.A) (BRK.B) and other hedge funds,

Warren Buffett’s Berkshire Hathaway revealed a position in embattled healthcare giant UnitedHealth Group while showing smaller stakes in longtime holdings Apple and Bank of America, according to a regulatory filing Thursday.

Berkshire Hathaway’s portfolio added six new stocks, including the three new secret stocks. Warren Buffett was a net seller of stocks for the eleventh straight quarter.

Warren Buffett's Berkshire Hathaway has placed a major bet on a recovery at UnitedHealth Group, disclosing a new $1.6 billion stake in the insurance giant.

Warren Buffett has requested confidentiality in a new Berkshire Hathaway position. Will investors find out the stock Thursday?