The news: Fast-fashion chain Primark said it would finally begin offering home delivery in the UK. This marks a notable about-face by parent company AB Foods, which has long claimed that low margins on the brand’s ultra-cheap products make it impossible to manage fulfillment costs.

Why it matters: Primark’s decision to invest more heavily in its ecommerce business comes amid considerable pressure from fast-fashion rivals. Its once unbeatable value proposition has been undermined by Shein, Temu, and more recently Zara’s sister brand Lefties, all of which offer products at similar—or cheaper—price points. At the same time, shoppers looking for higher-quality but still affordable clothing are more inclined to go to Zara and H&M than Primark.

That pressure is showing up in Primark’s performance. Same-store sales are expected to decline 2.6% this fiscal year, which ends on September 12. Total sales are forecast to rise just 2% despite double-digit growth in the US, underscoring difficulties in Primark’s home market as well as in continental Europe.

The question is whether Primark can make the math work. The brand claims that recent investments in ecommerce, including the purchase of an automated fulfillment center in Sheffield and expansion of its click and collect capabilities, have made profitable growth possible. At the same time, the brand is lowering prices across hundreds of items as it looks to win back cost-conscious shoppers while aggressively expanding in the US and other markets—all of which are pressuring Primark’s already razor-thin margins.

Implications for retail: Primark’s decision to offer delivery for online purchases could help strengthen the brand’s appeal to consumers who consider convenience to be an essential aspect of a company’s value proposition. That’s particularly true in the UK, where 42.1% of textile, clothing, and footwear sales come from ecommerce, per our forecast.

The move, alongside price cuts and stronger assortments, could enable Primark to claw back some share lost to Shein and keep newer entrants, like Lefties, from gaining traction at its expense. However, building a robust fulfillment network will be an expensive endeavor for a company with limited avenues for boosting profits.