The FTSE-100 Index has fallen 53.4 points after downbeat statements in the US from Compaq and software group Oracle. It now stands at at 5675.8.
Compaq said it planned to cut 5,000 jobs worldwide, while Oracle reported the downturn in IT spending had been worse than expected.
The comments from two of the sector's biggest players added to a long line of bleak trading statements this week, including from Cable & Wireless, Motorola and Ericsson.
As a result, the Nasdaq closed down , although the Dow Jones Industrial Average remained slightly ahead.
The news has led techs and telecoms stocks lower on this side of the Atlantic.
Sage is the biggest casualty of the Footsie, losing 9%, or 28½p, at 273p, while chip designer ARM Holdings is off 16p at 302p.
Telecom stocks in the red include Colt Telecom, down 46p at 950p, Energis off 13½p at 346½p, and Marconi down 14p at 413p. Vodafone is off 3¾p at 204¼p.
On a quiet day for corporate news, bus maker Henlys has moved ahead 7½p at 287½p, after reporting a 89% rise in pre-tax profits. The results were boosted by the newly acquired US school bus business Blue Bird.
Bank of Scotland, which announced a joint venture to supply services to customers of Zurich Financial Services, is up 10p at 673p.