MEXICO CITY, Feb 9 (Reuters) – America Movil, the biggest cell phone company in Latin America, posted a surprise 36 percent drop in fourth-quarter profit on Thursday as higher debt payments and a weaker peso offset a pickup in revenue.

The sharp slump was triggered by new debt America Movil took on to complete acquisitions as it tries to keep pace with peers and improve the speed and performance of its networks.

It was the second quarterly fall in net profits in a row for billionaire Carlos Slim’s flagship company, which has been hurt by a regulatory clampdown on fees charged to rivals for use of its network and is also battling a $1 billion fine for abuse of market power.

America Movil took on more debt in the quarter to finance its purchase of sister company Telmex and two smaller deals, which also weighed on quarterly earnings.

It was also hit by an 11 percent fall in the peso against the dollar in the fourth quarter, compared to the year-earlier period. About 80 percent of America Movil’s $28.9 billion debt is in foreign currencies, mostly U.S. dollars, although it earns more than 1/3 of its revenue in Mexican pesos.

“The results are not favorable for the company’s share price tomorrow,” said Santander analyst Gregorio Tomassi.

Before the results were released, America Movil shares closed up 0.13 percent at 15.56 pesos in local trading. The company’s shares, which make up almost one quarter of Mexico’s benchmark IPC index, have lost about 10 percent in the last 12 months, partly due to the tougher stance by regulators.

MEXICO CITY, Feb 8 (Reuters) – Mexican tycoon Carlos Slim’s mobile phone giant America Movil may have to do more than up its dividend or share buybacks to appease investors as it prepares to report another quarter of slow growth.

America Movil is seen posting a fourth-quarter profit increase of just 0.2 percent on Thursday, partly due to tougher regulation crimping margins.

Shares in the company, which posted a steep earnings decline in the third quarter, have lost more than 10 percent in the last 12 months as Slim battles a $1 billion fine and lower fees for allowing competitors to use his vast network.

“The market’s not expecting any surprises (from this report) precisely because of the lack of aggressiveness that America Movil has shown lately,” said Julio Zetina, analyst at Vector Casa de Bolsa in Mexico City.

Analysts often recommend America Movil shares to investors as a so-called “defensive play” in part because Slim, the world’s richest man, favors returning cash to shareholders – after all, his own family is the company’s biggest stakeholder.

The company’s biggest purchase in 2011 was the chunk of fixed-line operator Telefonos de Mexico (Telmex) that it did not already own and analysts do not see a large boost to the bottomline.

“There will be a bit of pressure on margins from the lower profitability of its Mexico fixed-line business,” said Manuel Jimenez, analyst at Banorte-Ixe in Mexico City.