Asos saw its profits plunge by nearly 90% to just £4 million in the six months to the end of February after what is described as a "difficult" year.
The online fashion retailer said heavy discounting and issues with traffic to its website were the main factors behind the decline. Asos altered its marketing strategy which impacted its search rankings.
It said sales performed well - up 14% to £1.3 billion during the period.
Chief executive Nick Beighton said it is aware of where it can improve and has "increased confidence" that performance will improve in the second half of the year after investing in its platforms.
"We now have the tech platform, the infrastructure, a constant conversation with our growing customer base who love our own great product and the constantly evolving edit of brands we present to them," said Mr Beighton.