The Fitch rating agency slashed BP's credit rating drastically six steps from AA to BBB Tuesday, on concerns about the cost of cleaning up the firm's Gulf of Mexico oil spill.
U.S. political leaders are asking BP to set aside billions of dollars in a special fund to be sure claims will be paid.
Some estimates put cleanup and other costs as high at $40 billion.
Rating agencies give lenders guidance on how likely a particular borrower is to repay its debt, and a lower rating is likely to mean higher interest charges.
Some information for this report was provided by AFP.