WASHINGTON: Ratings agency Moody's downgraded the credit ratings of several US banks on Monday and warned it was reviewing the status of some of the nation's biggest lenders.Moody's cut the ratings of 10 US banks by one notch and placed some banking giants on review for potential downgrades. The agency also changed its outlook to negative for several major lenders. Overall, it changed the assessments for 27 banks in the sector.The downgraded banks include M&T Bank, Pinnacle Financial Partners, Prosperity Bank and BOK Financial Corp.The banks placed on...