The purchases, made in November and December last year, come on top of a massive buyback effort by America Movil, whose share price has been under pressure since Mexico's government last year passed a reform plan that seeks to curb the company's dominance.

Slim's real estate company Inmobiliaria Carso and his bank Grupo Financiero Inbursa spent $212.5 million and $34.7 million purchasing 187.11 million and 30.98 million shares respectively in America Movil, a document sent to the U.S. Securities and Exchange Commission showed.

Slim, his three sons, three daughters and their controlled companies and foundations now own about 47.6 percent of America Movil's outstanding shares, up from 47.3 percent when the group made their last filing in November, according to a Reuters calculation.

The stake directly held by Slim has not changed from 4,950,586,338 million shares or 7.1 percent based on America Movil's total shares outstanding on Thursday, the filing showed.

The filing also shows that one of Slim's daughters, Maria Soumaya, sold 100,000 shares on December 30.

America Movil shares have fallen more than 10 percent this year, in spite of the company's continued buyback plan.

In 2013, the company spent about $5.4 billion, more than half its total capital expenditure for the year, buying back its own shares.

The shares closed 2013 up 2.14 percent, helped by the buyback.

America Movil shares closed down 2.05 percent on Thursday at 13.35 pesos, dragging Mexico's IPC index, which closed down 0.88 percent.

(Reporting by Elinor Comlay, additional reporting by Christine Murray; Editing by David Gregorio)