Barnes & Noble issued a statement Thursday afternoon rejecting a proposal made by a private equity firm to take the bookstore chain private.

In July, after acquiring a small stake in the retailer, Sandell Asset Management sent a letter to the B&N board urging the company to put itself up for sale. Among the options proposed by Sandell was for B&N to go private.

Since the letter, which contained few details about how any transaction should proceed, there has been little discussion about the possibility of a sale. At B&N’s annual shareholders meeting in September, the subject did not even come up. That changed Thursday when the Wall Street Journal reported that Sandell had made a proposal to take the company private.

In its statement, B&N confirmed Sandell offered to take B&N private in a deal valued at about $650 million. (Sandell currently owns slightly less than 3% of B&N’s shares.) Under the plan, existing shareholders, including company founder Len Riggio (who has an 18% stake in B&N), would put all of their shares into a new company that would be controlled by Sandell. The deal would also require $500 million in financing.

B&N said Riggio has “no intention of rolling his share into such a transaction.” Given the conditions, B&N said, it “does not take Sandell’s proposal as [a] bona fide” offer.