Out of the Gate: America Movil opens lower after downgrade

American Depositary Receipts of America Movil lost $7.11, or 10.9 percent, to $58.03. ADRs are securities that allow shares of foreign companies to be traded on U.S. markets.

Stephen Graham lowered America Movil to "Neutral" from "Buy" in a note to investors early Friday, a day after the Mexico City company said its first-quarter earnings fell a penny per ADR to 74 cents. The company attributed the decline to accounting changes instituted in January.

Analysts polled by Thomson Financial expected 88 cents per ADR, on average.

Graham said business slowed, was flat or shrunk across several of America Movil's service areas, including in Central America, Puerto Rico and Colombia. He said those figures, along with troubles at other Latin American telecommunications companies, suggest a slowdown is ahead.

"Various signs suggest that the sweetest spot of the company's growth curve has past," Graham wrote.

ADRs of America Movil have climbed about 33 percent from a 52-week low of $49.02 in January.