Dollar Thrifty Automotive Group Inc. (NYSE: DTG) shares added 12% Monday morning to $78.03, after Hertz Global Holdings Inc. (NYSE: HTZ) raised its offer to buy the rival car-rental company, hoping to outbid Avis Budget Group Inc. Volume for the stock was 1.27 million well before noon ET Monday.

It was Monday that Hertz offered Dollar Thrifty shareholders $72.00 per share (based on Hertz’s closing stock price on May 6), consisting of $57.60 in cash and 0.8546 shares of Hertz. The offer represents: a 26% premium and 18% premium to Dollar Thrifty’s 90-day and 60-day average share price, respectively; and a 24% premium to the value of the entirely hypothetical price announced by Avis over seven months ago.
Hertz’s offer is not subject to any financing condition or contingency

Commenting on the offer, Hertz CEO Mark P. Frissora said: “We believe that the acquisition of Dollar Thrifty by Hertz would be in the best interests of both companies’ shareholders and of rental car consumers, and that it will accelerate Hertz’s growth opportunities by leveraging the combined brand portfolio and unparalleled value and service reputations of both companies. To this end, we have today made a superior bid.”

Dollar Thrifty CEO Scott Thompson was not available for comment.