(Tulsa-AP) -- More tough news for Tulsa-based Williams Companies.
Moody's Investors Service cut Williams' credit ratings one notch to the lowest investment grade, ``B-a-a-3.''
The move comes in the midst of a wide-ranging federal investigation into energy-trading companies.
Moody's says Williams owns many assets that could generate relatively stable cash flows. But it says Williams' total cash flow from operations has been relatively weak and uneven.
Shares of Williams fell 23 cents yesterday to close at 8-dollars-70 cents on the New York Stock Exchange.
Williams says it's disappointed but not surprised by Moody's action.
The company says it's working to complete a debt-reduction plan that should resolve its credit rating problems.