Online fashion retailer Asos is poised to confirm that the billionaire retailer Mike Ashley has built up a stake of more than 5% in the company.

Asos’s statement to investors could come as soon as Monday morning, before the London Stock Exchange reopens after the weekend.

Ashley’s fashion and sportswear retailer Frasers Group informed Asos on Friday that it had become one of the company’s most significant shareholders. The move made Frasers the fourth largest shareholder in Asos. It was required to inform Asos once its stake in the company reached 5%.

Frasers first took a smaller stake in Asos earlier in the year, continuing the company’s record of building holdings in other retailers, making it one of the few businesses expanding on the high street. The increase in Frasers’ stake, first reported by the Telegraph, came after Asos reported slowing sales and a £32m pre-tax loss in the year to August.

Like many retailers, Asos has issued a profits warning as it struggles with rising energy and staffing costs, combined with the impact of a weak pound and shoppers reining in their spending amid the cost of living crisis.

Asos’s share price has plunged by more than 80% over the past year, and the retailer disclosed in recent days that it had agreed a £650m banking facility to give it “financial flexibility”.

The company said it would write off more than £100m of stock and cut its costs in response to tougher trading conditions.

Asos’s new chief executive said last week that the business had become too complex and had become “overstretched globally” as it attempted to attract shoppers outside the UK, in markets such as the US, France and Germany.

José Antonio Ramos Calamonte said it would work on buying its stock more frequently and closer to the time of sale, to make sure it had the right fashions to offer customers.

Frasers has continued to acquire other retail businesses in recent months: in July it snapped up the online fast fashion specialist I Saw It First, a month after buying the online fashion retailer Missguided out of administration for £20m in cash.

Ashley expanded his retail empire in 2018 with the purchase of the collapsed House of Fraser department store chain, and in recent years he has also invested heavily in the Flannels chain.

He stepped down from the board of Frasers Group earlier in October, after 40 years at the helm, when the company said he would not be standing for re-election as a director at the group’s annual meeting. However, he remains the company’s controlling shareholder, with a near-70% stake, and continues to act as an adviser to the board and senior management.

A Frasers spokesperson said only that the group “makes strategic investments in the ordinary course of its business, to develop relationships and partnerships with other retailers, suppliers and brands”.

Asos declined to comment on Frasers’ increased stake.