S1 Corporation up 31% on Acquisition by ACI Worldwide

S1 Corporation SONE is up 31% on Acquisition by ACI Worldwide ACIW. ACIW announced earlier today that it has proposed to acquire all of the outstanding shares of S1 Corporation for per share consideration of $9.50 in a cash and stock transaction valued at approximately $540 million. S1 Corporation is currently trading at $9.33, a gain of $2.20 or $30.87%.