Shares of NYSE Euronext (NYSE: NYX) have fallen considerably over the past month. The prime catalyst for the fall was a bearish note from an influential Goldman Sachs analyst, who lowered NYX from a neutral rating to an outright sell.

The rationale for the downgrade is a new rule dubbed "Regulation NMS" that's set to come into effect soon. Basically, this rule requires brokers to check prices on competing exchanges and systems to see if a better price is available before executing a trade. The rule is designed to ensure the best possible pricing for customers regardless of which exchange actually clears their trades. Since some contend that the Nasdaq market has faster technology than NYX, this new rule could slow down NYSE trading volume and allow the Nasdaq to grab more share.

However, the actual impact of this new regulation is likely to be marginal. To date, NYX has had little difficulty attracting new listings or generating trading volume and fees. We remain convinced that the firm's now-completed merger with Europe's Euronext offers some outstanding opportunities for the company to expand its business across the Atlantic and boost volume, regardless of Regulation NMS. NYX now operates six separate exchanges in five countries.

In fact, the company's recent earnings release simply reinforces confidence in this story. The firm easily topped analysts' revenue estimates, due mainly to a higher-than-expected total of 72 new listings on the exchange. Each new listing means additional fees for NYX -- and these results don't yet include Euronext.

Finally, it's unlikely that NYX will stop with Euronext. The company has already negotiated a closer alliance with the Tokyo Stock Exchange and has also taken a stake in India's main exchange. NYSE Euronext has established itself as a global leader, with the most flexibility to offer trading across multiple markets, products and time zones.

For more analysis from Paul Tracy, please visit www.StreetAuthority.com