Nasdaq OMX Group Inc. (NDAQ) said Monday that it had cancelled all business travel to Mexico, while other exchanges activated contingency plans in case the swine flu outbreak escalates into a pandemic.

The closure of financial markets in the wake of the Sept. 11, 2001, terrorist attacks has seen exchanges step up contingency planning, including health emergencies that may force staff and traders to work remotely or from home.

New York-based Nasdaq OMX joins a list of corporations worldwide that are limiting travel to Mexico, the center of the swine flu outbreak. The number of confirmed cases in the U.S. financial center is expected to climb toward 100.

Silvia Davi, a spokeswoman for Nasdaq OMX, said fallout from the outbreak is covered by its business continuity plan. Staff also have been prepared for the possibility of telecommuting if the problem deteriorates.

Contingency plans were also activated at other exchanges, though officials declined comment on specific details, citing security concerns.

Chicago-based CME Group Inc. (CME) on Monday circulated a memo to employees and exchange members, passing along swine flu information from the Centers for Disease Control and flu prevention tips.

"We believe these proactive actions help to ensure the well-being of the CME Group community," CME said in a statement.

ChicagoFirst, a business continuity non-profit group that counts CME, NYSE Euronext (NYX) and the Chicago Board Options Exchange as members, distributed information from city and state officials.

"Exchanges and other members do have within their plans work-from-home and telecommunications provisions," said ChicagoFirst Executive Director Brian Tishuk, in an interview with Dow Jones Newswires. "To the extent that's feasible, they do plan to do that."

Tishuk said that member companies of ChicagoFirst, which has had a pandemic working group in place since 2006, have tested their crisis-response plans within the past year.

-By Jacob Bunge, Dow Jones Newswires; (312) 750-4117; jacob.bunge@dowjones.com