By Ananya Mariam Rajesh

(Reuters) -Macy's has ended its buyout talks with Arkhouse Management and Brigade Capital due to uncertainty over financing and valuation and said it would now concentrate on its turnaround efforts, sending its shares down 15% on Monday.

The company disclosed that the investor group had revised its offer for a second time in June to buy the department store chain's stock it does not already own for $24.80 apiece, up from $24 per share offered in March.

The latest bid valued Macy's (NYSE:M) at $6.86 billion and was at a nearly 43% premium to the stock's close on Dec. 8, when the news of the offer first emerged.

Arkhouse, which has a 4.4% stake in Macy's, and Brigade Capital Management did not immediately respond to a Reuters request for comment.

Macy's, which had opened its books to the investor group, had said in April two of Arkhouse's nominees would join its board's finance committee, which was responsible for overseeing the evaluation of the buyout proposal.

"It seems like ... it didn't work out to Macy's satisfaction. I think Macy's was probably anticipating that it would be raised by a few dollars, not 80 cents," Morningstar analyst David Swartz said.

The deal talks came at a crucial time when Macy's, which traces its roots to a dry goods store set up in New York in 1858, rolled out a turnaround plan under new CEO Tony Spring that focused on job cuts and 150 store closures through 2026.

Macy's said on Monday its board intends for the management team to return its full focus on enhancing shareholder value through the execution of the turnaround plan.

A hostile acquisition by the investor group would be extremely expensive and there is no guarantee it would work even if the offer is raised again, since Macy's is looking to focus on its new strategy, Swartz said.

Macy's raised its annual profit forecast in May betting on Spring's strategy, though sluggish demand pressured sales.

Peers Nordstrom (NYSE:JWN) and Kohl's (NYSE:KSS) have also attracted buyout interests, especially for their real estate assets.

Shares of Kohl's and Nordstrom were down about 3% each.