Gap Inc. (GPS.N) tumbled in early trading after the clothing retailer reported a slump in sales at both its namesake line and Old Navy, threatening the potential appeal for a spinoff of the discount chain.

Same-store sales, a key measure of a retailer’s performance, fell four per cent companywide, worse than the estimate compiled by Consensus Metrix. Weakness at the Gap brand appears to be deepening, with comparable sales down 10 per cent, more than double the projection.

A turnaround doesn’t appear imminent: Gap Inc. now expects same-store sales for fiscal 2019 to be down in the low single digits after cold, wet weather weighed on the first quarter. The shares fell 17 per cent in premarket trading Friday. The news also dragged Swedish rival Hennes & Mauritz AB shares down as much as 5.7 per cent and Spain’s Inditex 3.3 per cent lower.

Gap Chief Executive Officer Art Peck said “this quarter was extremely challenging, and we are not at all satisfied with our results.” He said the company is still “confident” in its plan to spin off Old Navy.

That chain, which is now the company’s biggest revenue generator, had a 1% drop in same-store sales, compared with an estimate for growth of 0.8 per cent.

The company’s selection of clothing appears to be a key part of the problem. Chief Financial Officer Teri List-Stoll said Gap held back on marketing support during the first quarter in part because the merchandise wasn’t up to par.

Gap shares have lost more than a fifth of their value in the past month, adding pressure for the company to provide more details about its plans. Investors will have to wait several months, though: Peck said the company, which has formed a spinoff team, is planning a mid-September event to talk about it.