The FTSE-100 Index has charged ahead 119.2 points after Marconi lifted the tech and telecom sector with a better than expected trading statement.
Although the telecoms equipment giant announced 3,000 redundancies there was no profits warning, improving shares 6%, or 19½p, to 329½p.
The Footsie now stands at 5782.5.
Other telecom stocks rose, including Spirent which rose 31¼p to 336¼p after receiving a multi-year contract to supply hardware and software for Qwest Communications, a leading local exchange carrier in the US.
Among the telecoms stocks to rise are Energis, 25¾p stronger at 280½p, Cable & Wireless ahead 21p to 525½p, Vodafone up 10¼p at 215¾p and BT rising 23p to 574p.
Among the tech stocks on the way up are Misys, up 36p to 436p, Arm Holdings, up 16p to 271p, and Logica, up 40p to 810p.
Tesco has dropped 13½p to 256p despite posting pre-tax profits 13% ahead at £1.05 billion.
Other retailers on the way down are Marks & Spencer, off 4¾p at 255½p, while Dixons is off 1¼p at 268p.
And supermarket chain Morrison's first day in the FTSE-100 Index has seen its shares slip 7¼p at 207¾p.
But Debenhams is up 12¼p to 430p after reporting a 9% lift in half-year pre-tax profits.