Asos founder Nick Robertson has sold shares in the fashion etailer worth £20m following a turbulent year for the business.

Robertson’s disposal of 744,600 shares, reportedly prompted by a “big tax bill” leaves him with an 8.4% stake in the fashion etailer.

The share sale comes after a turbulent year for Asos, which has been hit by difficulties in overseas markets and a fire at its warehouse. It had to warn on profits three times.

Analysts said the disposal might cause others to follow suit.

Liberum analyst Tom Gadsby said: “Short-term share price reaction is notoriously hard to predict but clearly a major share sale by the founder is hardly a positive signal.”

He feared that Asos may face further business challenges.

Gadsby said: “What was previously a low-risk ‘pull’ model where customers worldwide ordered stock from the Barnsley warehouse – ie, low stock risk, not weather-dependent, limited markdowns - has become a more traditional model where Asos must send out stock to warehouses across the world and second-guess weather and customer demand, implying much higher markdown risk.

“As a fast-fashion retailer, short lead times and small order sizes mean that the company does not get the bulk-buying benefits that a traditional retailer such as Next or H&M might get.”