SAO PAULO, Aug 15 (Reuters) - Preferred shares of Brazil's state-run oil producer Petroleo Brasileiro SA jumped on Friday as investors upped their bets that President Dilma Rousseff would fail to win re-election in the first round of October's presidential race.
The death of presidential candidate Eduardo Campos in a plane crash on Wednesday triggered bets that his popular running-mate Marina Silva would head his party's ticket, making it harder for Rousseff to win the race outright.
Investors are hopeful that a new administration would enact policies that are more favorable to the interests of Petrobras' minority shareholders. Some analysts said the market action may be exaggerated by the expiration of stock option contracts on Monday.
At 3:48 p.m. (1848 GMT), Petrobras preferred shares were up 6.67 percent to 19.84 reais, while common shares rose 6.06 percent to 18.54 reais. (Reporting by Asher Levine; Editing by Chris Reese)