THE WOODLANDS, Texas (AP) — Huntsman Corp., the nation's fourth-largest chemical company, said a private-equity firm has made a cash buyout offer of about $6 billion that trumps a bid from a Dutch company announced last week.The proposal from Apollo Management's Hexion Specialty Chemicals Inc. of Columbus, Ohio, values Huntsman at $27.25 per share, Huntsman said in a statement. The offer is an eight percent premium over the $25.25 per share bid from Basell AF, a Dutch holding of U.S. industrialist Len Blavatnik's Access Industries.

There were 221.9 million outstanding shares of Huntsman stock when the Basell offer was announced last week. The stock price jumped 20 percent after the Basell announcement. Shares closed Tuesday at $24.40 after starting last week at $19.01.

Hexion's offer to buy Huntsman is contingent on Huntsman's rejection of the Basell offer, which was about $5.6 billion in cash. Basell would get $200 million if its offer is canceled, and Huntsman said Hexion has agreed to pay half of that if the new offer goes through.

The Huntsman board unanimously approved the Basell deal but subsequently decided the Hexion offer could "reasonably be expected to lead to a superior proposal." Huntsman said its transaction committee was evaluating the terms of Hexion's offer.