Separately, the French and Spanish derivatives exchanges announced their intention to co-operate, a development seen by many as further evidence of the trend towards consolidation of financial exchanges.
Members of the American Stock Exchange (Amex) voted by 622 to 206 in favour of the merger with Nasdaq, comfortably above the two-thirds majority required. The exchanges announced plans to join forces earlier this year.
Charles Balfour, managing director of Nasdaq International, said: "It's very good news for them and it's very good news for us. It will help shape the future of the securities market in the global marketplace."
At the end of 1997, 5,466 companies were listed on Nasdaq, with a total value of pounds 1,165bn. Amex had 783 firms with a total value of pounds 103bn. Their combined US equity market share will be 47 per cent.
The Nasdaq/Amex merger, which will include the Philadelphia Stock Exchange, will give the exchanges a combined market share of the US options market of 50 per cent.
Mr Balfour declined to comment on the "talks about talks" between Nasdaq and Deutsche Borse, the German exchange. The two are understood to be considering linking systems and initiating joint marketing, but are thought unlikely to agree a full merger.
Meanwhile Matif, Monep and Meff, the French and Spanish derivatives exchanges, said they planned to create a partnership called Euro Globex. A spokeswoman for Liffe, London's futures and options exchange, said it had no plans to link with any other exchange.Reuse content