Macy’s investor Arkhouse Management said on Thursday the US department store was in talks with the investment firm for opening its books for due diligence on the prospects of a higher offer.

Arkhouse disclosed its move in a regulatory filing, saying this was in response to a letter from Macy’s on March 11 that called the latest offer as “less than compelling” and that the board was “not prepared to transact at this price level.”

The firm and Brigade Capital had on March 3 raised their offer to $24 apiece for the shares they did not already own, valuing Macy’s at $6.6 billion, while leaving the door open for a higher bid.

Arkhouse and Brigade have provided a due diligence request list to Macy’s, which includes customary items that it will need to provide to confirm or potentially increase the offer, Arkhouse disclosed in the filing.

“Negotiations with respect to the confidentiality agreement remain ongoing and Arkhouse Management and Brigade continue to await access to the requested diligence materials,” it said.

Arkhouse has a 4.4 percent stake in Macy’s along with its affiliates. The company declined to comment.

The investment firm has nominated nine director candidates including executives with retail, real estate and capital markets experience, to the 14-member board of Macy’s last month, kicking off a proxy battle.

Shares of the company were up nearly 4 percent on Thursday.

By Savyata Mishra and Svea Herbst-Bayliss; Editing by Arun Koyyur

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Activist Investors Raise Macy’s Buyout Bid to $6.6 Billion

Investment firms Arkhouse Management and Brigade Capital Management is offering to acquire Macy’s stock they don’t already own or $24 per share, 14 percent above its previous offer from December.