Then there is the George Soros angle.

The New York-based hedge fund firm controlled by the billionaire philanthropist and backer of Democratic causes and campaigns bought and sold millions of shares in Petrobras -- the largest of the firm's holdings -- prior to public disclosure of the Export-Import bank's offer of new credit guarantees to the Brazilian energy giant.

No one has accused Soros of wrongdoing, but some say the transactions do not pass the "smell test."