John Reed, who retired as chairman and co-chief executive of Citigroup in April 2000, is to serve as interim head of the exchange.

But Mr Reed said he would not be putting himself forward as a permanent candidate for the position.

Richard Grasso resigned his position as chairman and chief executive of the NYSE last week following increasing controversy over his $140m pay package and criticism from key pension funds.

'Perfect' candidate

On Friday, the NYSE appointed a Wall Street executive - Laurence Fink, the chairman of investment management firm BlackRock - to head up the search for Mr Grasso's successor.

Attempts to find a swift replacement for Mr Grasso had foundered, with top Silicon Valley lawyer Larry Sonsini, TIAA-CREF mutual fund boss Herbert Allison Jr, and former US Treasury Secretary Robert Rubin all ruling themselves out of the job.

"The committee worked Friday night and throughout the weekend and looked at 12 possible candidates," Mr Fink said.

"John was at the top of the list, and was the only person to whom we offered the position.

"His qualifications matched perfectly the criteria we used to evaluate potential candidates."

Reform looms

Mr Reed declined to comment on Mr Grasso's departure, but said he was aware of the problems the exchange was facing.

"I have seen crises quite comparable to what the NYSE has gone through... and clearly it did not help anyone," he said.

The departure of Mr Grasso has led to calls for reform of the way the exchange operates

It has come under criticism that its members - whom the exchange is supposed to regulate - may have too much influence over the pay of its top executives.

Measures suggested include splitting the NYSE's chief executive and chairman's roles, and ditching its regulatory role altogether.