(Adds expected date of shareholders assembly, background on deal)
By Tatiana Bautzer and Alberto Alerigi
SAO PAULO, Nov 27 (Reuters) - Brazilian restaurant operator International Meal Company Alimentação SA is expected to call a shareholder meeting to consider adding takeover protection to its bylaws on Dec. 13, a source with knowledge of the matter said.
Shareholders owning a combined 18.31 percent stake in IMC, as the company is known, sent a letter to the company proposing that any investor offer to acquire a stake of 30 percent or more should be extended to all shareholders, the company said in a securities filing earlier.
The proposal is what is commonly known as a "poison pill" clause.
Brazilian asset managers such as XP Investimentos and Neo signed the letter, which was addressed to the company board. IMC has among its relevant shareholders U.S. private equity firm Advent International Corp.
Earlier in November, holding company Abanzai Representaçoes, a vehicle owned by competing Brazilian firm Sapore, said it planned to buy up to 42 percent of the company for 8.63 reais per share at an auction on Dec. 19.
A second step in the proposed deal after successful completion of the auction would be a merger between IMC and privately-held Sapore. Shares in IMC were up 1.3 percent, at 6.87 reais, in early afternoon trading in Sao Paulo.
If approved, the poision pill provision would effectively block the Sapore deal.
Another source, who has direct knowledge of the Sapore bid, said on Monday that the company would not be able to obtain financing to buy more than the 42 percent stake it has proposed to acquire.
Both sources asked for anonymity due to a lack of authorization to speak publicly on the matter.
Sapore and IMC did not immediately reply to requests for comment. (Additional reporting by Alberto Alerigi; Editing by Bernadette Baum and Tom Brown)