Online fashion retailer ASOS said today that its chief executive Nick Robertson is to step down with immediate effect from the helm of the company he founded 15 years ago.

Mr Robertson will become a non-executive director at the firm that targets fashionable 20-somethings and will be replaced as chief executive by current chief operating officer Nick Beighton.

Mr Robertson founded ASOS, which stands for As Seen on Screen, in 2000. The company was floated on London’s junior market in 2001 with its shares worth 20p, but are now currently worth around £28 each, valuing the business at £2.4billion.

Mr Robertson oversaw the growth of the brand from a UK business to one with international operations in countries such as the United States, France and Australia.

ASOS chairman Brian McBride praised Mr Robertson’s “extraordinary achievement”. He added: “His passion and vision have built a start-up into a world class company. We are all delighted that Nick will continue to contribute to the company that he started.”

ASOS said in June it expected to see its full-year revenues come in at the top end of its expectations with a rise of 15% to 20%.

This is would represent a recovery after a tough 2014 that saw it issue a string of profit warnings amid tough overseas trading and a costly warehouse fire.

The company is also part of the way through a programme that has seen it roll out local pricing in Australia, France, Germany, Spain, Italy and the US recently, enabling it to sell goods at more competitive rates and sell brands which were previously restricted in these territories.

It said its price investments had driven overseas sales growth over the four months to the end of June, which also helped offset the impact of a raft of currencies weakening against the pound.

The fashion site, which sells more than 80,000 branded and own-brand products to 9.7million customers, said Mr Beighton joined six years ago as chief financial officer, before being promoted to his current post last October.

A spokesman said Mr Beighton would continue the strategy of changing the firm’s pricing structure in the different markets it operates in, and upgrading its IT base.

Mr McBride called Mr Beighton an “able successor” who has “unique experience of the company built over six years”.

Mr Robertson retains an 8.5% stake in the business.

Independent retail analyst Nick Bubb said Mr Beighton “has been well groomed” for his new role.

However, Mr Bubb said the timing of the change was “pretty abrupt”, adding the firm’s new finance director Helen Ashton only started her role yesterday, after leaving a senior role at debt management business Capquest.