Bank stocks are under pressure early Tuesday after rating agency Moody's downgraded ten small regional banks and placed several larger banks on review for downgrades. Moody's said the rating action reflects the ongoing strain in the US banking sector, including increased funding pressures and potential regulatory capital weaknesses rising risks associated with commercial real estate exposures. The firm downgraded ratings of M&T (NYSE: MTB ), Amarillo National Bank, Old National (NASDAQ: ONB ), Commerce Bancshares (NASDAQ: CBSH ), Associated Banc-Corp (NYSE: ASB ), BOK Financial (NASDAQ: BOKF ), Webster Financial (NYSE: WBS ), Prosperity Bancshares (NYSE: PB ), Fulton Financial (NASDAQ: FULT ), and Pinnacle Financial Partners (NASDAQ: PNFP ).