By Svea Herbst-Bayliss

NEW YORK (Reuters) -Billionaire investor Ryan Cohen is building a large stake in Nordstrom Inc and plans to push the upscale retailer to shake up its board as its performance has lagged behind rivals, people familiar with the matter said on Thursday.

Cohen, who built his fortune by co-founding online pet retailer Chewy Inc and cemented it with investments in videogame retailer GameStop and Apple Inc, would like to replace at least one director on Nordstrom's 10-member board, the people said.

He appears to be taking aim at Mark Tritton, who chairs the compensation committee and has served as a director since 2020. Cohen has privately called Tritton, a former chief executive of Bed Bath & Beyond, "conflicted and unqualified," said the people, who were not permitted to discuss the private negotiations. Bed Bath & Beyond is preparing to file for bankruptcy, Reuters reported this week.

Investors cheered Cohen's reported involvement at Nordstrom by sending the stock price up 25% in after-hours trading on Thursday.

Nordstrom shares have dropped roughly 55% over the past five years, and ratings agency Fitch again downgraded the company last month, saying that its "operating trajectory has been weaker than most retailers."

"While Cohen hasn't sought any discussions with us in several years, we are open to hearing his views, as we do with all Nordstrom shareholders," a company representative said.

The Wall Street Journal first reported Cohen's stake in Nordstrom.

Cohen is now one of the company's top five non-insider shareholders alongside investment firms BlackRock and Fidelity, the people familiar with his stake said.

Tritton was ousted as Bed Bath & Beyond's CEO as part of a management shakeup in June just a few months after Cohen had taken a stake in the home goods retailer and criticized it for an "overly ambitious" strategy, for overpaying executives and failing to reverse market share losses.

As possible replacements on the Nordstrom board, Cohen has identified executives with experience at retail and e-commerce companies, the people said. Cohen would like to reach a deal with the company without resorting to a proxy fight, the people said.

The window to publicly nominate directors at Nordstrom closes on Feb. 17, according to proxy materials.

Canada-born Cohen, 37, has a net worth estimated at $2.5 billion. He made a splash in the investing world two years ago when he joined the board of GameStop, igniting a frenzy in the stock price that turned the video retailer into a "meme stock" backed by retail investors.