The 2001 switch to decimal share pricing, from sixteenths of a dollar, allowed any firm willing to sell for a penny less than the best available price to step in and make the trade. That reduced margins for specialists on the floor of the exchange. Automated-trading firms such as Getco LLC in Chicago used high-speed computers on electronic venues such as Bats Global Markets in Kansas City, Mo., and Jersey City, N.J.-based Direct Edge Holdings LLC to overcome lower profits by sending thousands of orders to trade every second.

Ways To Grow

At the same time, exchanges around the world were combining, with at least $95.8 billion of mergers completed since January 2000. NYSE combined with Euronext NV in 2007. TMX bought Montreal Exchange Inc. in 2008, a year after London Stock Exchange Group acquired Borsa Italiana SpA. ICE purchased the New York Board of Trade in 2007 and Bolsa de Mercadorias e Futuros bought Bovespa Holding SA in 2008.

Futures exchanges around the world traded 8.2 billion contracts in 2009, almost three times the turnover in 2003, according to data from the Futures Industry Association.

With rivals taking business, one of the quickest ways for NYSE Euronext to grow is through mergers and acquisitions, said Michael Pagano, a professor of finance who studies exchanges and market structure at the Villanova School of Business in Villanova, Pennsylvania.

'Just Electricity'

"It costs a fixed amount of money to build a computer system for trading, but once you generate revenue that covers those fixed costs the marginal cost of covering just one additional trade beyond that is basically just electricity," Pagano said.

That's led to a reduction in costs. Total salaries and benefits at NYSE fell by 5.6% to $613 million last year, the biggest drop since the data on the publicly traded company began in 2005. Deutsche Boerse, which is scheduled to release results next week, cut staff expenses by 3.7% in 2009 and 26% in 2008, according to data compiled by Bloomberg.

NYSE Euronext owns exchanges in Amsterdam, Lisbon, Paris and Brussels, as well as London-based Liffe, Europe's second-largest derivatives market. The company also runs three U.S. stock exchanges: NYSE Arca, NYSE Amex and the New York Stock Exchange, two options platforms and the NYSE Liffe U.S. futures exchange, which trades contracts linked to interest rates.

Deutsche Boerse operates the Frankfurt stock exchange and Clearstream, Europe's second-biggest securities-settlement firm. The company also has Eurex Clearing AG and a 50% holding in Eurex, the region's largest futures market. Eurex bought a stake in International Securities Exchange, an options market that competes with CBOE, in 2007.