Under Armour's “Unlike Any” campaign featuring Zoe Zhang.

The ath-leisure trend may be coming to an end and athleticwear giants are going to see some fallout.

Wells Fargo analyst Tom Nikic said in a new report that consumers over the last several years have “filled their closets with athleticwear” that has crossed into casualwear from the likes of Nike, Lululemon and Under Armour. But having bought enough — and combined with some bankruptcies of sports retailers and a lack of product innovation — the sector may be heading for a slowdown.

“Big picture…the category appears poised to take a breather for now,” Nikic said.

This led him to lower full-year earnings estimates for Nike, Lululemon and Under Armour, but Nikic also downgraded the latter to underperform from market perform, saying the company looks likely to be hit hardest by sales leveling off.

Deutsche Bank in July downgraded Under Armour to “sell” from “hold” over its dwindling near-term growth prospects and the company cut its annual revenue projection less than a week later. Under Armour posted its first-ever loss during the first quarter.

Nikic explained that Under Armour still operates mainly in the struggling U.S. retail market and is sold more as performance gear, unlike Nike and Lululemon, while its sneaker offering has “more customer attrition than any other brand,” according to the results of a survey.

While “cracks started to show” in the industry last year as growth slowed to 6 percent, the lowest rate since 2010, Nikic said headwinds are expected to continue into 2018 as sales trends have continued to “deteriorate” this year.

As for Nike, which is expected to deliver financial results for its first fiscal quarter next week, Nikic said the recent launch of the Vapormax sneaker hasn’t grabbed the “sneaker-buying community,” and that its recent deal with Amazon could negatively affect the brand’s retail presence.

“The cannibalization risk would be high if Nike ever began selling premium sneakers directly to Amazon,” Nikic said.

He also noted that 40 percent of more than 550 young men surveyed on their buying habits in the athletic sector said they would buy premium sneakers on Amazon if they were available.

At the moment, Nike only sells “mass” product on Amazon retailing under $90.

Nikic admitted that Lululemon “seems to have the most momentum” among the three brands, but he pointed out that its positive financials have been driven entirely by price increases over the last year or more and store traffic has been negative, presenting a risk “if/when Lulu can no longer push higher pricing.”

Lululemon in August posted a 10 percent decline in second quarter net income, while net revenue increased 13 percent and comparable sales, including digital, increased 7 percent.

Adidas was characterized as a “bright spot” in the industry, but Nikic pointed out that its business has been driven with fashion, not performance product.

“The athletic industry was able to avoid some of the issues that have plagued the rest of retail for years (negative traffic, aggressive promotions, etc.) but now that demand is cooling off, they can no longer avoid these headwinds,” Nikic said.