[Editor’s note: This story was updated at 2:25 p.m. on April 20, to reflect the correction at the bottom of the article.]

A $75 million price hike has restarted the bidding war for CKE Restaurants, the Carpinteria-based parent of Carl’s Jr. and Hardees.

CKE said April 18 that it has received a buyout offer worth $75 million more than the previous offer from Boston-based private equity firm Thomas H. Lee Partners, or THL. The new bidder is offering $12.55 per share, compared with THL’s offer of $11.05 a share.

The new offer is from an unidentified bidder believed to be affiliated with buyout specialist Leon Black. It works out to about $694 million in cash, compared with THL’s $619 million bid. The premium more than covers the $15 million breakup fee plus up to $5 million in costs that CKE will pay if it walks away from THL, and amounts to about $75 million more than the THL deal.

THL had also offered to take on about $300 million in CKE debt. But CKE said the new bid was a “superior proposal” after its legal team examined it.

Under its agreement with THL, CKE has to give the Boston firm four days of negotiations to make a better offer. If not, CKE said it expects to accept the new offer and deliver the paperwork to seal the deal by April 24.

On Feb. 26, CKE agreed to a buyout by THL for $928 million in cash and the assumption of $309 million in net debt. The potential deal represented a payout for the underperforming burger maker’s battered shareholders and executives.

But on April 7, CKE said it had received a late bid that might top THL’s offer. It didn’t announce the bidder or the price, but Reuters, quoting unnamed sources, said the rival is Apollo Management, part of Black’s business empire.

After the announcement of the THL deal, executives at CKE sought to reassure the company’s 179 employees on the South Coast that not much would change after a buyout. But Black has a history of replacing executives at his acquisitions and shook up management at retailer Linens ’n Things and Vail Resorts after purchasing them.

CKE’s stock was up 6.7 percent to $12.80 in midday trading.

[Editor’s Note: The initial version of this story contained incorrect information about the name of the entity that made the latest bid.]

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