The Ibovespa (IBOV) gained for the third time in four days as oil producer Petroleo Brasileiro SA advanced amid speculation that a potential change in government will reduce intervention in state-owned companies.

Lender Banco do Brasil SA, which is also owned by the federal government, was the best performer on the MSCI Brazil/Financials index. Retailer Lojas Renner SA advanced as traders pared bets on higher interest rates in Brazil. Phone company Oi SA dropped after reporting a second-quarter loss that was wider than analysts had forecast.

The Ibovespa climbed 0.7 percent to 56,571.05 at 12:08 p.m in Sao Paulo after falling as much as 0.9 percent earlier today. The real rose 0.2 percent to 2.2775 per U.S. dollar. Petrobras jumped 2.8 percent to 20.25 reais amid speculation that President Dilma Rousseff will lose her re-election bid in October. An Ibope election poll commissioned by Globo TV may be released tomorrow, according to the electoral court website.

“In Brazil, the main driver for the market is still the elections,” Rogerio Freitas, a partner at hedge fund Teorica Investimentos, said by phone from Rio de Janeiro. “Stocks will continue to react to every poll that comes out.”

Brazil’s benchmark equity index has rallied 25 percent from this year’s low on March 14 as polls started showing Rousseff losing support.

Banco do Brasil gained 1.6 percent today to 28.29 reais.

Ukraine Turmoil

The Ibovespa fell earlier today as concern the Ukraine crisis will escalate curbed demand for emerging-market assets. A gauge of shares in developing nations slid after a spokeswoman for the North Atlantic Treaty Organization said there’s a risk of Russia sending troops into Ukraine under the “pretext” of a humanitarian or peacekeeping mission.

Oi tumbled 3.7 percent to 1.29 reais after reporting an adjusted net loss of 220.9 million reais in the second quarter. Analysts surveyed by Bloomberg had predicted a loss of 207.3 million reais.

Car rental company Companhia de Locacao das Americas added 3.6 percent to 4.94 reais after posting earnings that topped analysts’ estimates. Eighteen of 31 companies on the Ibovespa that have already reported second-quarter results missed earnings estimates, according to data compiled by Bloomberg.

Trading volume of equities in Sao Paulo was 6.57 billion reais yesterday, compared with a daily average of 6.5 billion reais this year, according to data from the exchange.