Underscoring the sensitivity of both EWZ and Petrobras to polling data, the stock has rallied on days when news favors Neves because he has promised “to auction exploration licenses more frequently, raise fuel prices and ease made-in-Brazil requirements mirror recommendations from the industry,” report Sabrina Valle and Juan Pablo Spinetto for Bloomberg.

Under Rousseff, shares of Petrobras have languished and the company’s debt burden as swelled as hostile government policies have kept Western oil producers from partnering with Petrobras to tap Brazil’s bountiful oil reserves, which are among the largest for a non-OPEC nation. [Energy ETFs are Voting for Neves]

While a Neves win would appear to be a boon for EWZ and Petrobras, investors cannot forget the inherent volatility in Brazilian data. That volatility was on display last week when after starting the week sharply higher, EWZ and Petrobras closed the week in the red after polling data should Neves and Rousseff in a dead heat. Investors also pulled over $293 million from EWZ last week after pouring $908.5 million into the ETF as it slumped during the third quarter.

iShares MSCI Brazil Capped ETF