Aug 12 (Reuters) - Nelson Peltz's Trian Fund Management is forming a consortium of investors for a take-private bid for US fast-food chain Wendy's, according to a source familiar with the matter.

The group could include Bugatti-backer BlueFive Capital and Flynn Group, one of the burger restaurant's longest franchisees, and a bid could be submitted in the coming weeks, the source said.

Shares of the company were up about 15% on Wednesday.

Trian, a longtime Wendy's shareholder, holds a 16.24% stake and would be compelled to unveil any formal offer in a regulatory filing. Trian holds 7.85%, according to a February filing.

The exact timing of the bid could change, sources cautioned. The Financial Times first reported the news on Wednesday. 

Wendy's, which has a market valuation of about $1.44 billion according to data compiled by LSEG, said it would thoroughly review any proposal submitted by Trian consistent with its fiduciary duties, while Trian did not immediately respond to a request for comment.