S&P Global has revised the prospects of five regional banks in the United States from stable to negative. This downgrade is attributed to the potential risks associated with commercial real estate (CRE). What Happened: The outlooks of First Commonwealth Financial (NASDAQ:FCF), M&T Bank (NYSE:MTB), Synovus Financial (NYSE:SNV), Trustmark (NASDAQ:TRMK), and Valley National Bancorp (NASDAQ:VLY) were downgraded by S&P Global, according to a Reuters report. Their heightened exposure to CRE loans justified this move. The downgrade has sparked concerns amongst investors regarding the banking sector’s…