SAO PAULO, Jan 28 (Reuters) - Brazil's main stock index sank on Wednesday as shares of state-run oil company Petrobras plunged on concerns over potential losses stemming from a multibillion-dollar corruption scandal.
The benchmark Bovespa index dropped about 1.4 percent and was on track for its weakest closing level in over three weeks, while the broader MSCI Latin American stock index erased the previous session's gains.
Petrobras released unaudited third-quarter results on Wednesday after months of delays, though the statement left investors in the dark over the financial impact of the kickback scheme that investigators unveiled last year.
Preferred and common shares of Petroleo Brasileiro SA , as the company is formally known, both shed about 12 percent, their biggest loss in three months.
"It's quite frustrating," wrote analysts at Brazilian brokerage Planner in an investor note. "Everyone was waiting for these numbers in order to have some kind of measure of the losses and the value of the company's assets."
Investors began dumping the stock last year on concerns over the re-election of President Dilma Rousseff, whose government enacted fuel price policies meant to control inflation at the expense of the firm.
Now, uncertainty over the size of the potential corruption-related losses and Petrobras' repeated delays in publishing financial information have added a new scare.
Petrobras preferred shares are down about 60 percent since Sept. 1.
In currency markets, the Brazilian real gave up nearly all of the previous session's gains against the dollar, with some traders saying they will stay cautious until the U.S. Federal Reserve issues its next policy statement later in the day.
Colombia's peso strengthened slightly, while Chile's peso was little changed. (Reporting by Asher Levine and Priscila Jordao; Editing by Meredith Mazzilli)