CHICAGO (From news reports) -- R.R. Donnelley & Sons Co. continues to back a takeover offer from Atlas Holdings LLC and said its board rejected all alternative acquisition agreements.

A "go-shop" clause allowing the company to solicit other offers has now expired and the communications and marketing company said its board determined that there were no assurances that a deal could be reached or consummated based on rival approaches from Chatham Asset Management LLC and an unnamed strategic party.

Affiliates of Atlas have agreed to acquire the company for a $8.52 a share in cash. R.R. Donnelley in mid-November received an unsolicited proposal from Chatham offering $9.10 a share cash, and it said that on Nov. 28 it received an alternative acquisition proposal from a strategic party for $10 a share cash.

R.R. Donnelley said that its board reaffirmed its recommendation of the merger agreement with Atlas.

The company noted that under the Atlas agreement, it would be required to pay a $20 million termination fee and reimburse any expenses to Atlas if the company terminates the agreement.