Smurfit-Stone Container Corp. (SSCC) received an offer prior to the $3.5 billion bid from RockTenn Co. (RT), but rejected it as too low, according to a merger proposal outlining the terms of RT’s pending acquisition, reports the St. Louis Post-Dispatch.

The merger proposal, filed with the U.S. Securities and Exchange Commission (SEC) on Feb. 25, indicates that an unnamed suitor contacted SSCC’s board of directors in September 2010 to inquire about a possible sale.

The company, which was listed only as Party A, then made a nonbinding offer in November to acquire 100 percent of SSCC for $29 per share, which was rejected as too low at an emergency meeting of SSCC’s board of directors in mid-December.

RT initially offered $32 per share in December, in half cash and half stock, and increased that to $35 per share on Jan. 23. SSCC’s board did not contact Party A or other parties about making higher bids because it didn’t think it would get a higher bid than RT’s, according to the merger proposal.

While SSCC was going through bankruptcy proceedings, sell- ing the company was explored, but interested buyers were unwilling to proceed with a transaction, according to RT’s SEC filing.

Three hedge funds that jointly hold 9 percent of SSCC have previously said they will vote against the sale to RT. In a Feb. 2 letter to SSCC’s board, Third Point, Royal Capital Management and Monarch Alternative Capital called the sale a “steal” and claimed that proper sale procedures were not followed.

The funds are not expected to be able to block the sale, but their objections could signal discontent with the deal from holders of SSCC common stock.

The merger of the two companies has received antitrust clearance from the U.S. Federal Trade Commission, as well as approval from both companies’ boards of directors, but must still be voted on by shareholders.