Fashion retailer SuperGroup has issued a shock profit warning after uncovering maths errors in its forecasting.

The retailer, founded by entrepreneur Julian Dunkerton, also flagged the phasing of wholesale revenues and retail margins as factors resulting in profits now expected to come in at £43m rather than the £50m previously expected.

In the first 10 minutes of trading on the Stock Exchange this morning, SuperGroup lost a third of its value.

SuperGroup, which owns the trendy Superdry brand, reported that “there have been arithmetic errors in our forecast of the wholesale business amounting to some £2.5m”.

Difficulty forecasting wholesale demand “given our rapid expansion and lack of history” led to another £2m shortfall in current year numbers.

On the retail front, SuperGroup revealed that “the mix of sales through our various channels” has hit margins.

The retailer said: “We took the decision to increase our operating costs in order to ensure that we had the correct product at the right time in each of our retail channels, and also, to accelerate investment in our management team.”  

Those factors totalled about £2m.

SuperGroup floated in March 2010 and its shares have had a roller-coaster ride since, following a series of setbacks particularly in the supply chain.

Singer analyst Matthew McEachran said: “This latest calamity in SuperGroup’s short life as a listed company is not going to be well received. And the shares will come under severe pressure.