Lululemon Athletica has trimmed its full-year sales and profit outlook for the second time this year, as a persistent slump in its Americas segment continues to weigh on results.

The athletic apparel retailer said on Thursday it now expects annual revenue to land between $10.35 billion and $10.5 billion, down from its prior range of $11 billion to $11.15 billion. Earnings per share are projected at $9.48 to $9.73, compared with the earlier forecast of $10.95 to $11.15 per share.

Management attributed the cautious guidance to industry-wide challenges that have not let up over recent quarters. Co-CEO and Chief Financial Officer Meghan Frank noted that while the company anticipated its turnaround plan would take time, market reception has been weaker than expected heading into the second half of the year.

Shares plunged 17% in after-hours trading to $100.18 following the announcement. For the year to date, the stock has tumbled 42% through Thursday's close.

Executives said second-quarter results were hurt by negative online sentiment toward the brand, a factor also cited when the company first lowered its outlook in June. A string of new product launches has underwhelmed, while many North American shoppers have shifted to competitors like Alo and Vuori.

"Overall reception to our new products has been mixed, and we continue to see brand pressure across both of our core markets," Frank said.

Second-quarter revenue fell 4% year over year to $2.42 billion, missing the $2.46 billion analysts had anticipated. Americas revenue dropped 8%, while international sales rose 4%. Comparable-store sales declined 9%, well below Wall Street's expectations of a 4.6% decrease.

Lululemon has been working to push full-price selling and reduce promotional activity, but Frank said sales of key items like leggings and women's tops have slowed more sharply than expected.

Profit for the quarter came in at $329.2 million, or $2.92 per share, down from $370.9 million, or $3.10 per share, in the same period last year. The latest quarter included a tax refund and related interest income of 86 cents per share after taxes.

For the third quarter, Lululemon forecasts revenue between $2.29 billion and $2.32 billion, below analysts' estimates of $2.53 billion, with earnings per share expected at $0.93 to $0.98.

The results arrive just as Heidi O'Neill prepares to step in as the company's new chief executive next week. Investors are counting on her to steer a turnaround after the brand weathered several public setbacks.

Earlier this year, Lululemon reached a settlement with founder Chip Wilson, who had spent years publicly criticizing the company and attempted to reshape the board through a proxy fight. As the largest shareholder, Wilson agreed to a non-disparagement clause in exchange for the right to nominate two board directors.

O'Neill's appointment initially triggered a share decline, with investors questioning her track record at Nike. Analysts suggest she should halt store expansion, focus on repairing North American sales, and refocus on core products and classic color offerings.