An $8 billion exchange merger is in the works that underscores how the global market for derivatives has eclipsed that for stocks.

The owner of the venerable New York Stock Exchange is in talks to be acquired by an upstart commodities and derivatives trading platform, according to people briefed on the matter. The IntercontinentalExchange is expected to offer about $33 a share, with two-thirds of that in stock, one of these people said. That represents a premium of 37 percent to NYSE Euronext's closing stock price on Wednesday. A deal could be announced as soon as Thursday morning.

While the New York Stock Exchange, with its opening bell and floor traders, has been the public image of a stock market for two centuries, it is NYSE Euronext's businesses in the over-the-counter trading of derivatives -- including the Liffe market in London -- that appear to be the main attraction in the merger talks.

IntercontinentalExchange, or ICE, was founded in 2000 and is based in Atlanta. It competes fiercely with the CME Group, a derivatives trading powerhouse that owns the Chicago Mercantile Exchange and the Chicago Board of Trade.

More than a year ago, ICE teamed up with the New York exchange's chief rival, the Nasdaq OMX Group, to make a hostile bid for NYSE Euronext. The Justice Department threatened to block that joint offer, but the newest merger might pose fewer problems because ICE focuses on commodities like oil, natural gas and cotton, while NYSE Euronext plies mainly in stock and stock options and derivatives.