CKE Restaurants Inc. is reported to have agreed to be acquired by private equity firm Thomas H. Lee Partners under a $619 million deal. The announcement made its shares to grow up by 25 percent in trading before the bell.

CKE stockholders will receive $11.05 in cash per share of CKE common stock they hold, the companies revealed today in a statement. The proposal values the company at $11.05 a share, a premium of 24 percent over CKE's Thursday closing price of $8.91.

Sales at CKE restaurants open at least a year registered a slip of 6 percent in the quarter ended Jan. 25, as unemployment continued to be on a high and competitors reduced hamburger prices.

CKE, known for its oversized hamburgers and provocative advertisements, said the private equity firm will also assume about $309 million of its net debt.

However, CKE, the parent of the Carl's Jr. and Hardee's brands, posted that it will actively look for superior offers from third parties for the next 40 days.

CKE claimed UBS Investment Bank will be its financial advisor and it hopes the deal to close in the second quarter.