SAO PAULO, Sept 17 (Reuters) - Latin American stocks and currencies reacted mildly to the U.S. Federal Reserve's policy statement on Wednesday, although Brazilian assets swung on the release of an electoral poll.
The Fed renewed a pledge to keep interest rates near zero for a "considerable time," as expected. Latin American financial markets moved slightly after the announcement, only to return to their previous levels.
Instead, investors in Brazil kept their focus on October's presidential election. A poll released on Tuesday showed President Dilma Rousseff losing ground slightly in a presumed second-round vote to challenger Marina Silva.
Investors have been critical of Rousseff for enacting policies they see as detrimental to the private sector and state-run companies.
"Sentiment on the sovereign and on the country's financial market dynamics are being increasingly driven by poll results and less by the country's fundamentals or even U.S. Fed policy," Oxford Economics analyst Aryam Vazquez wrote on Wednesday.
The Bovespa stock index rose nearly 1 percent, driven by a 3 percent gain in shares of state-run oil producer Petroleo Brasileiro SA.
Mexican and Chilean stocks also posted modest gains that were little swayed by the Fed statement.
Analysts said the Fed did not make enough significant changes from its previous statement to drive a big move in either direction.
The broader MSCI Latin American stock index rose for the third straight session, adding 0.5 percent.
In currency markets, The Brazilian real traded about 0.6 percent weaker against the dollar, while the Chilean peso dropped about 0.7 percent ahead of a market holiday on Thursday and Friday.
Argentina's black market peso dropped to 15 per U.S. dollar, its weakest on record. The peso has tanked more than 15 percent since the government defaulted on its debt on July 31, crashing through a succession of historic lows as Argentine businesses and savers seek refuge in dollars. (Reporting by Asher Levine; Editing by James Dalgleish)