Shares in the telecoms equipment maker - now called Marconi Corporation - began trading at 60.5p valuing the company at �605m ($980m).

The shares climbed to 62p, but by lunchtime they had fallen to 58.5p.

Shares in the old Marconi were delisted on Friday after the complex restructuring of its �4bn debt pile was given the go-ahead.

Under the terms of the 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.

Existing shareholders will get one new Marconi share for every 559 old Marconi shares.

Looking to the future

The company was forced to take drastic action after it borrowed heavily to fund an acquisition spree just as the telecoms boom was coming to an end.

Marconi was left with huge debts and a range of overpriced assets whose value was steadily dwindling.

Its market value peaked at about �35bn in the late 1990s boom.

Three years ago shares were trading at �12.50, but last Friday they closed at just 0.8p.

After two years of shareholder anger and tough negotiations with creditors, the company's managers were relieved to be starting again.