The impact of the escalating violence appears to have had a more psychological than practical effect on multinationals operating businesses in Mexico. In a July report, Standard & Poor's said equipment manufacturers continue to expand their operations in Mexico, drawn by low wages and the fact there are no tariffs on vehicle parts imported to the U.S. The ratings agency acknowledges that the increasing violence is a risk for companies, but so far not one that outweighs the benefits.

“We haven't seen any evidence of disruptions in this or any other important industries within the country,” the S&P report says.

Mexico's current country-risk assessment from Coface puts it at the same level as up-and-coming Colombia, which was upgraded to A4 from B in 2007. Zlotowski notes that the country assessment is separate from Mexico's business-environment assessment, which remains a relatively strong A4—the same as Brazil's and Colombia's.

“In terms of financial transparency, it's a rather good country. But the macroeconomic and political environment is a bit more fragile than we had thought,” Zlotowski says.

Mexico also tends to be more open to foreign investment than many emerging markets. Its derivatives exchange, for example, allows for remote memberships, so non-Mexican broker-dealers can become members without incorporating in the country, potentially facilitating corporate clients' hedging opportunities.

In addition, Daniel Perkins, a member of Accenture's treasury management practice, points out that unlike most developing countries Mexico has permitted foreign banks to join its clearing system. “So multinational firms can use those banks to collect local payments,” Perkins says.

See more stories here about countries where multinationals have spotted opportunities.