The share was to be taken off the London Stock Exchange when the markets closed, and will be replaced with shares in the newly-restructured Marconi Corporation on Monday morning.

The switch follows a breakthrough in protracted negotiations regarding the restructuring of Marconi's �4bn debt pile on Thursday, and signals a dramatic shift in Marconi's ownership.

Under the terms of the debt restructuring deal, owners of the old Marconi plc shares will receive just 0.5% of the new stock, with the remainder going to the company's long-suffering creditors.

On Thursday, Marconi said a US bankruptcy court had cleared the way for the restructuring to be completed.

Riches to rags

The changeover draws a line under one of the most spectacular share price collapses that the UK has ever witnessed.

Marconi's market value hit a peak of about �35bn at the peak of the late 1990s boom, but later fell steeply as investor disenchantment with the much-touted internet and telecoms-based "new economy" set in.

The decline accelerated sharply in July 2001 when a shock profits warning cut its share price in half, reducing its value to �3.5bn.

Mounting debt problems and a prolonged downturn in the telecoms equipment market have piled further pressure on the company ever since.

Marconi shares were worth just 0.62p on Friday morning, valuing the company at just over �16m.

By the close, the shares had risen to 0.8p.

The company's dramatic fall from grace is cited as a cautionary tale of managerial misjudgement.

New beginning

In a previous incarnation, Marconi was the defence and electronics firm GEC, a cash-rich industrial giant which had begun to look staid as the fashion for high-growth internet and telecoms stocks took hold in the late 1990s.

Its metamorphosis began under former chief executive Lord Simpson, who took over from GEC's long-serving boss Lord Weinstock in 1996.

Determined to turn GEC into a major telecoms player, Lord Simpson sold off its defence assets, changed its name to Marconi, and borrowed heavily to fund an acquisition spree aimed at building up its presence in the telecoms sector.

Unfortunately, he completed the transformation just as the telecoms boom was coming to an end, leaving Marconi with hefty debts and a range of overpriced assets whose value was steadily dwindling.

The new Marconi shares are expected to change hands at about 48p, reflecting the company's more solid financial footing now that its debts have been restructured.