Updated from 5:06 a.mRONKONKOMA,, N.Y. ( TheStreet) -- NBTY ( NTY), the nutritional supplements maker, has agreed to be acquired by private-equity firm Carlyle for $55 a share in cash, or $3.8 billion. NBTY has a market cap of $2.4 billion and annual revenue of about $2.6 billion. The shares closed Wednesday at $37.47. In a statement Thursday, NBTY said the value of the deal is a premium of about 57% over the stock's average closing price during the 30 trading days to Wednesday.>P/>The news confirms published reports earlier that Carlyle and Blackstone ( BX) were eyeing NBTY. NBTY sells products under brands Solgar, Rexall and MET-Rx. -- Reported by Joseph Woelfel in New York. Get more stock ideas and investing advice on our sister site, Stockpickr.com.