Tapestry's Coach brand finished the fiscal year with another standout quarter of sales growth, but investors are worried the company won't be able to keep momentum going for another year.

Coach has wowed shareholders this year, as its handbags caught on with Gen Z shoppers and found viral success with some products including the Brooklyn Bag. But Tapestry struck a note of conservatism Thursday and said it now expects revenue to slow down in the second half of its new fiscal year.

Shares of the fashion company were down 15% to $130 Thursday morning.

Tapestry, which also owns Kate Spade, expects to generate $8.4 billion to $8.5 billion in sales during the new year, compared with analysts' forecast of $8.47 billion. It anticipates $7.80 to $7.90 in earnings per share, while analysts were looking for $7.87 a share.

Tapestry expects revenue will slow to a mid-single-digit percentage in the second half of the year, after rising in the high-single digits during the first half, executives told analysts on a call.

The guidance assumes Coach's sales growth will start the year at a similar clip to the quarter before, but doesn't require Tapestry to keep up with that same level of growth as the year stretches on, Chief Financial Officer Scott Roe said.

"Our outlook reflects that confidence, but also discipline in how we give guidance and how we plan," Roe said.

Coach sales increased 15% to $1.64 billion in the fiscal fourth quarter, offsetting a 7% decline in Kate Spade revenue. Total sales were up 9% to $1.88 billion, just above analysts' estimate of $1.87 billion.

Profit was $347.8 million, or $1.68 a share, compared with a loss of $517.1 million, or $2.49 a share, a year earlier.

Stripping out certain one-time items, adjusted per-share earnings were $1.32, ahead of the $1.28 anticipated by analysts, according to FactSet.

Roe noted that Tapestry is still navigating macroeconomic uncertainty and changing tariffs, which are expected to result in uneven profitability across quarters. The company expects a modest benefit from tariffs in the first half of the year, which will turn into a headwind in the second half.

During the current first quarter, Tapestry expects $1.55 in earnings per share, ahead of the $1.49 a share analysts are anticipating.

The company said its board approved a 16% increase to its quarterly dividend at 46.25 cents a share and expects to buy back $1.35 billion in shares this fiscal year under its existing share repurchase authorization.