Lululemon founder Chip Wilson is not happy with the brand.
He recently wrote an open letter to shareholders, since he wasn't permitted to speak out at a board meeting, saying that the company has "lost its way."
He said that Lululemon "cannot continue to cede the market opportunity we created to Under Armour and Nike."
Meanwhile, Wilson told Business Insider that he's been profiting from Under Armour's and Nike's success.
"Here's a fact I think is unbelievable and it's sad for everybody except for me and Nike and Under Armour," he said in a phone interview with Business Insider. "I've made all my money in the last two years betting on Nike and Under Armour stock because I haven't been able to trade Lululemon."
He sold 50% of his Lululemon shares about two years ago, he said.
In his letter, he wrote that "Under Armour has taken our leadership role, and the market recognizes this with a premium valuation."
Under Armour's CEO, Kevin Plank, has said that he plans to double the company's women's sector, which would thereby trump Lululemon.
"Kevin has put out a vision again," Wilson said. "He's seeing into the future, he knows how big the marketplace is, and they seem to be putting down the building blocks to take advantage of it, where Lululemon again is just building out more store, building out e-commerce."
In his letter, he pointed out that, since Lululemon's CEO, Laurent Potdevin, took hold in 2013, Under Armour's stock has increased 79% and Nike's has increased by 45%, but Lululemon's has decreased by 8%.
He told Business Insider that Nike is "pushing technology," specifically with its Olympic apparel.
"I think, you know, Under Armour's in the middle because I think they push technology, but they've got a wholesale model where their customers won't pay for it, but it's good marketing," he said.
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