Carmike Cinemas shares are up 3.7%  to about $31.34 in afternoon trading after a leading shareholder opponent of AMC Entertainment’s takeover offer switched to favor the deal.

Dreihaus Capital Management, which owns about 10% of Carmike, says that it will begrudingly “vote a substantial majority of our shares in favor of the transaction”

The investment firm still believes that AMC’s sweetened $1.2 billion offer — cash and stock equal to $33.06 a share — “does not equitably share the value created from the prospective transaction.”

But even though Carmike’s standalone value is “substantially in excess of the $33.06 per share offer” Dreihaus is “not as confident that it would be one year from today given management’s focus on selling the company rather than growing it.”

Believing that AMC stands to see a big boost from the combination, making it the world’s No. 1 exhibition chain, “we began to establish a position in AMC’s shares following the July 25 announcement of its revised proposal.”

AMC chief Adam Aron told analysts this week that the company has made “our best and final offer…I shudder to think what would happen to Carmike share performance” if investors reject its offer and AMC walks away. “They now have a real decision to make.”