Asos chairman Waheed Alli has cashed in nearly half of his £30m stake in the online fashion retailer.

Labour peer Alli used an option to snap up 750,000 Asos shares at 12.67p last week before immediately selling them at £19 per share – pocketing a profit of £14.15m.

The transaction sliced more than 5% off the Asos market value on Friday.

The sell-off is believed to have been sparked by Alli’s recent lost investment on the media group Chorion.

In the past two years Asos’s share price has shot up 500%. However a recent move to offer free shipping combined with concerns the company is overvalued has put the share price into shakier territory.

Alli still owns 830,000 Asos shares, worth £15.7m.

Sales at Asos in the year to March 31, increased by 52% to £339.7m, but pre-tax profit fell 23% to £15.7m. International revenues more than doubled to £140m.

The online company has a sales target of £1bn by 2015.