The stock is down 15% as analysts question the yoga-wear maker's fashion assortment

Lululemon reported second-quarter results on Thursday.

Lululemon Athletica is in the midst of a struggle to win over investors and consumers - as evidenced Thursday by its declining second-quarter sales and reduced full-year outlook, which come just days before a new CEO comes aboard.

Shares were tumbling 16.2% after hours on Thursday.

Lululemon (LULU) said it expects sales for the year to land within a range of $10.35 billion to $10.5 billion, which would mark a decline of 5% to 7%. That's worse than the company's forecast in June for $11 billion to $11.15 billion in sales.

"While we continue to navigate some challenging dynamics, we are taking a prudent approach with our revised full-year outlook," Meghan Frank, Lululemon's interim co-CEO and chief financial officer, said in the company's earnings release.

Lululemon delivered the results and the forecast as analysts await the arrival of Lululemon's new CEO, Heidi O'Neill, a veteran of Nike and Levi's, who takes over on Sept. 8. She will be arriving during a difficult year for Lululemon, following concerns over its product quality and style relevance, as well as a board dispute with founder Chip Wilson.

Other issues, like cautious consumers and competition with Alo and Vuori, have weighed on Lululemon's stock. Shares of Lululemon have fallen 41% so far this year.

Analysts have questioned the company's fashion choices and criticized it for departing from its core athletic gear. Lululemon has expanded into things like rugby shirts, charms and collaborations with brands like Disney.

For the second quarter, Lululemon's sales fell 4% to $2.42 billion. Analysts polled by FactSet expected $2.46 billion. Same-store sales, or those made at established stores, fell 9%, compared with Wall Street's estimates for a 4.6% drop. Lululemon earned $2.92 a share during the quarter, topping estimates for $1.79.

Jefferies analyst Randal Konik said in a note ahead of the release that along with shedding "disjointed" color schemes and logo-heavy designs, Lululemon also needed to fix its company culture. Next year, he said, would likely be about "the timing of any fruits of Heidi's labor."

-Bill Peters