Asos boss Nick Robertson insists the etailer’s profit warning is just a “bump in the road”, but have the wheels come off UK etail’s biggest success story?

The City has not proved forgiving and Asos’s share price has plummeted 30% after this morning’s profit warning.

It is a dramatic fall from grace for the etailer, which has been a darling of the stock market for the past five years.

What is viewed as Asos’s great strength – its international prowess – has been its downfall over the past year as it has grappled with exchange rate fluctuation.

Its lines once seemed like the ultimate bargain to fashionistas in countries such as Australia because currency exchanges made Asos less pricey than local rivals.

However, now the tides have turned and the strong British pound has made Asos’s products seem on the expensive side.

Robertson says he suffered a “triple whammy”. Not only did sales slow overseas, but those sales were his most profitable – Asos makes more money from countries such as Australia – and to get rid of excess stock he was forced to promote and reduce margins in the UK.

It’s a problem that comes with being a global business, which, it’s worth recalling, is what Asos has been incredibly successful in becoming.

And Asos is not alone in suffering - Burberry has also flagged the impact of currency on its business this year. In fact, Robertson says it’s something that all UK exporters should be aware of.

There are some lessons to learn for the etailer. Of course, Asos has no control over currency fluctuations but it could have acted to lessen the impact on its business. The main problem is that Asos did not have the flexibility to react to currency changes, says N+1 Singer analyst Matthew McEachran.

Asos is frantically working on introducing zonal pricing. However, that will inevitably lower prices overseas, which will continue to impact margins.

McEachran also says Asos was forced to mark down products because of its stock holding. “I’ve always thought its stock turn was quite high. This will allow people to look at aspects of the business they had questions over which are easy to overlook when it’s growing at the rate of Asos,” he says.

Asos finance director Nick Beighton admitted to analysts this morning that it had learned a “legacy lesson” that random promotions don’t necessarily help.

Robertson told Retail Week the excess stock forced him to promote but insisted the etailer is better prepared to deal with this because “we now know what the run rate is”. This suggests that Asos may cut its cloth accordingly to reduce stock holding.

It should be remembered that Asos is a business that has had few setbacks in what has been a phenomenal growth story. And that is what today’s profit warning is, according to McEachran - a setback rather than a crashing failure.

“Asos is still a quality business. They hit a very substantial headwind. It’s set it back a year but it will continue to grow,” says McEachran.

So perhaps investors should forgive Asos for today’s slip, if it can learn and adapt for the future.