Petróleo Brasileiro S.A. - Petrobras saw a decline in short interest during the month of May. As of May 31st, there was short interest totaling 23,520,000 shares, a decline of 19.8% from the May 15th total of 29,340,000 shares. Based on an average trading volume of 21,070,000 shares, the short-interest ratio is presently 1.1 days. View Petróleo Brasileiro S.A. - Petrobras' Short Interest .