Shares of marketing company Cossette Inc. gained more than 58 per cent Monday after a former executive at the company made an unsolicited bid to take over the firm.

Quebec City-based Cossette said Cosmos Capital Inc. has made a bid to buy all the company's subordinate voting shares for $4.95 apiece. Cosmos is controlled by Francois Duffar, who used to be vice-chair and president at Cossette.

Shares of Cossette jumped $1.90 to close at $5.15 on the Toronto Stock Exchange. The stock has a one-year high of $6.74 and a low of $2.78.

Cosmos said its offer represents a premium of more than 52 per cent from the July 17 closing price of Cossette's shares on the TSX.

Also in the Cosmos group is Georges Morin, who resigned on July 18 from his roles as a director and senior vice-president at Cossette. Former BCE CEO Jean Monty is also in the bidding group.

Cosmos said it currently has about more than 2.9 million of Cossette's multiple voting shares and 205,733 of the company's subordinate voting shares, representing 18.7 per cent of the shares of Cossette on a diluted basis. Burgundy Asset Management, which is supporting Cosmos' bid, owns 11.1 per cent of Cossette.

"We are seeking to work together with the board of directors and holders of multiple voting shares of Cossette to conclude a supported transaction that is compelling to the shareholders, clients and employees of Cossette," Duffar said in a release.

Duffar said a reorganization of the company's resources and capital "will lead to a more efficient and dynamic Cossette." He said the company's head office will remain in Quebec.

Active in advertising and public relations, Cossette has 1,485 employees in offices in Quebec City, Montreal, Toronto, Vancouver, Halifax, New York, Irvine, Calif., Los Angeles, London and Shanghai.