Shares of Luluemon have cratered as quickly as its sales momentum.

The Canadian retailer's stock tumbled more than 23 percent Thursday, hours after the athletic wear maker warned its fiscal first quarter has gotten off to a slow start amid a sea of drab clothes.

Specifically, weak store traffic and fewer online purchases are setting the chain up for its first quarterly comparable sales decline since the recession.

The news was an abrupt pivot from its fourth-quarter performance, when both sales and earnings posted double-digit gains. At least four analysts on Thursday downgraded the company's shares, citing concerns about its about-face.

Lululemon's warning added to concerns about a slowdown in the athletic apparel market, which has also been seen in recent results from Under Armour and Nike.

The company's shares were on pace for their second worst day of trading in history.

"In what should have been a fairly tame print from Lululemon (holiday sales [were] already pre-announced), their fourth-quarter results uncovered several issues that are likely to create an overhang on the stock for the foreseeable future," Wells Fargo analyst Ike Boruchow told investors.

Boruchow on Thursday downgraded Lululemon's shares to market perform from outperform.

Among those issues are that its steep drop-off occurred both in stores and online. Lululemon CEO Laurent Potdevin attributed the deceleration to a bland assortment that lacked color, and uninspiring presentation of the products on its website.

On a call with investors outlining its results, Potdevin told investors that the steps it is taking to correct these problems are already showing results.

He added that trends should improve in the second quarter and beyond as the company rolls out new sport bras and its first global marketing campaign.

Yet Wall Street wasn't convinced. Given the broader slowdown in apparel sales and a crowded athletic wear market, it cautioned that Lululemon's optimism is likely premature. And after steadily driving its gross margin higher over the past several quarters, that metric is expected to be flat during the current fiscal year.

Despite Lululemon's near-term shakiness, the company reiterated that it's on track to double its 2015 revenue and earnings by 2020. Analysts were likewise more optimistic about its prospects longer term, noting its white space in the U.S., internationally and within its menswear business.

"Lululemon has significant room to grow the brand," Citi analyst Paul Lejuez said in a research note while downgrading the stock to neutral from buy. "However, the path to long-term growth is not as visible against the backdrop of the current weakness."

Lululemon shares are down more than 21 percent this year.

For more on Lululemon, tune into "Mad Money" Thursday at 6 p.m. EDT for an interview with CEO Laurent Potdevin.