The latest proposal by Vector Capital-backed Certara to acquire Symyx Technologies for $5.75 per share in cash has been rejected by Symyx's Board of Directors. Certara originally made a $6.75 per share bid but replaced it with a $5.75 per share bid. When that proposal was rejected, Certara modified the proposal. The latest proposal was once again rejected due to financial inadequacy and issues concerning a guarantee of the deal. Symyx, which is being advised by UBS and Cooley on the transaction, is still in favor of a bid from Accelrys (NASDAQ: ACCL).