Shares in Belfast-based engineering group Powerscreen took a dive yesterday after a parcel of stock was sold at a substantial discount to the prevailing market price, dealers in London said.

The stock fell by 21 per cent or 36p sterling, to 155p (133.5p sterling), after a block of 690,000 shares changed hands at 133p sterling. At the time, the quote on the London Stock Exchange was 160p sterling.

Powerscreen issued a profit warning in January following the discovery of irregularities in its Matbro subsidiary. Matbro is now the subject of a Serious Fraud Office investigation. Powerscreen shares started the year at 608p sterling.