Shares in SuperGroup dropped after it emerged that the young fashion business, which has a strict no-discounting policy, offered some online customers 20% off in-store purchases last weekend.

Shares fell 68p to 969p as investors were unsettled by the initiative.

Arden analyst Nick Bubb said: “The bears got very excited on Friday about the news that online customers of Superdry got a voucher for 20% off everything in-store at the weekend, despite the long-standing policy of not discounting.”

House broker Seymour Pierce said that rattled investors should not see the promotional activity as a change in strategy and is “not in any way a change in policy re discounting”.

A SuperGroup spokesman said: “It wasn’t a discount it was a short term marketing promotion, just a one off.”

Meanwhile, shares in British luxury label Burberry rose on speculation that it was eyeing a takeover of iconic US luxury jewellery chain Tiffany.

Luxury good groups Richemont and PPR have both also been linked as potential suitors.