CHICAGO (From news reports) -- R.R. Donnelley & Sons Co. fell after saying an unidentified bidder has withdrawn its offer to buy the printing company for $11.50 a share.

The suitor didn't provide specific reasons for its withdrawal, R.R. Donnelley said in a statement Wednesday. The Chicago-based company reaffirmed its recommendation for shareholders to vote for the Chatham Asset Management LLC offer of $10.85 a share at a meeting on Feb. 23.

The mystery party had been circling since at least November but has never been named in R.R. Donnelley's public statements. The unsolicited offers started during a two-month bidding war between Chatham and Atlas Holdings, which Chatham ultimately won.