NYSE Euronext shares are now trading in Paris and New York

The world's largest stockmarket group closed at 73.8 euros in Paris, marking a 3% rise on its 72-euro opening price.

But by close of trade in New York shares in the exchange were 3.4% lower at $97.5, having opened at $100.

The dual-listing crowns a year-long process to merge the New York Stock Exchange with Euronext.

The first inter-continental market will oversee New York, Paris, Lisbon, Amsterdam and Brussels exchanges.

A leviathan worth 19bn euros ($25.4bn; �12.9bn), NYSE Euronext currently has listed companies worth a total $28.5 trillion, including what it says are 78 of the world's top 100 largest businesses.

'Global leader'

"NYSE Euronext is the global leader and we have significant business opportunities ahead of us," said chief executive John Thain, who attended the start of trading in Paris.

Mr Thain and his deputy Jean-Francois Theodore are flying to New York in time for Wall Street's closing bell.

The group is hoping customers will be attracted to the flexibility of trading stocks, bonds and derivatives across time zones, so permitting the buying of company stock in Paris and selling it in the US or vice versa.

It also said $375m of cost saving through shared administration and computer systems could be expected by 2009.

Identities retained

NYSE and Euronext committed to a 10.9bn euro merger last June after Euronext rebuffed a rival offer from Deutsche Bourse.

The deal was finally concluded in March after NYSE investors took control of 91.4% of Euronext's shares.

The two companies retain their separate identities, their specific trading arrangements and their trading hours.

Crucially, companies quoted on each market will continue to operate under existing regulations.