New York Community Bank on Wednesday promoted its chairman to help stabilize the company’s operations. Late Tuesday Moody’s Investors Service downgraded NYCB’s credit ratings two notches to junk. The regional bank has been in free fall, shedding more than 50% of its market value across a punishing series of trading sessions, since reporting a surprise fourth-quarter loss last week. ... New York Community Bank on Wednesday promoted its chairman to help stabilize the company’s operations, hours after Moody’s Investors Service downgraded the bank’s credit ratings two notches to junk. Shares gained nearly 7% Wednesday after initially falling as much as...