(Adds stocks performance, quote from economist, background)
By Walter Brandimarte
RIO DE JANEIRO, July 18 (Reuters) - Brazilian financial markets rallied on Friday after a poll showed President Dilma Rousseff and opposition candidate Aecio Neves statistically tied in a possible second-round vote in October.
Investors have been increasing their bets that the opposition may win this year's presidential elections, defeating a government they accuse of intervening excessively in the economy.
The real , which had posted a sharp loss on Thursday on global geopolitical fears, rallied 1 percent to 2.2344 per dollar. It had closed the previous session weaker than 2.25 per dollar for the first time since the beginning of June.
Brazil's benchmark Bovespa index jumped nearly 3 percent as shares of Petróleo Brasileiro SA gained almost 5 percent. The financial performance of Petrobras, as the state-run oil company is known, has sharply deteriorated under a government policy that forces it to subsidize fuels in the domestic market.
"Investors consider a possible policy change as positive and are buying Brazilian assets," said Jankiel Santos, chief economist with Espírito Santo investment bank in São Paulo.
The latest Datafolha poll released Thursday night showed Rousseff with 44 percent of voter support and Neves with 40 percent in a possible second-round vote, within the survey's margin of error.
Rousseff still leads the race in the first round scheduled for Oct. 5 with 36 percent of support, down from 38 percent in the previous poll. Neves has 20 percent of support, unchanged from the previous survey. (Additional reporting by Bruno Federowski; Editing by Jeffrey Benkoe and Lisa Von Ahn)