Colombian oil company Ecopetrol overtook Brazilian energy firm Petrobras earlier this week to become Latin America's largest public company by market value, according to a study by Sao Paulo-based consultancy Economatica.

Though their shares are publicly traded, both companies are controlled by their respective governments.

Ecopetrol's market capitalization, or the value of its outstanding shares, rose to $126.72 billion at Tuesday's market close from $89.4 billion at the end of December, when it ranked as the fifth-biggest company, the study said.

Petrobras' market value, meanwhile, fell from $155.44 billion at the end of 2011 to $123.86 billion at Tuesday's market close, the study added.

According to Economatica, a decline in Petrobras' share price in recent weeks coupled with the sharp depreciation of the Brazilian real relative to the U.S. dollar in 2012 have caused the company's market capitalization to plunge to its March 2009 level.

Ecopetrol's market value now also is higher than that of Brazilian mining conglomerate Vale, which currently ranks fourth with a market capitalization of $96.59 billion, down from $105.53 billion in December when it was in second place.

Vale also was leapfrogged by Brazilian brewer AmBev, whose market value rose from $99.99 billion at the end of last year to $109.76 billion on Tuesday.

Mexico City-based telecom giant America Movil remained in fifth place with a market capitalization of $94.62 billion at Tuesday's market close, while Brazilian banks Itau-Unibanco and Bradesco stayed in sixth and seventh place with market values of $61.13 billion and $49.96 billion, respectively.

Wal-Mart de Mexico, $47.12 billion; Santander Brasil bank, $29.94 billion; and state-controlled Banco do Brasil, $29.48 billion, currently hold positions eight through 10.