NEW YORK (TheStreet) -- Endo International (ENDP - Get Report)  reached a deal to buy Auxilium Pharmaceuticals (AUXL) for $33.25 a share in cash and stock.

The acquisition is valued at $2.6 billion.

Auxilium shares closed Wednesday at $29.76 and were soaring almost 16% in premarket trading to $34.45.

Late last month, Endo made a takeover offer for Auxilium that was valued at about $2.2 billion. Auxilium said at the time that the Endo offer "significantly undervalues" the company.