First Republic Bank absorbed debt rating downgrades from two bond rating firms Wednesday, as concerns mounted it will suffer further deposit flight that will hurt its already modest profitability. S&P Global Ratings downgraded its issuer credit rating on First Republic Bank by four notches to BB-plus from A-minus, placing it in speculative grade, or ‘junk,’ status, in a move that came just hours after it put the bank’s debt on review. Fitch…