US bank stocks steady but credit concerns persist

** Shares of U.S. banks mixed after falling sharply premarket

** Citigroup C up 0.3%, Bank of America BAC up 1.2%; Morgan Stanley MS, JPMorgan JPM down 0.2% and 0.5%, respectively

** U.S. banks and broader markets sold off sharply on Thursday amid concerns about bad loans for regional banks

** Zions Bancorporation ZION up 5% following 13% plunge in previous session after lender discloses a $50 million loss on two commercial loans from California division

** Western Alliance WAL up 2.6% after falling 10.8% a day earlier; bank said initiated a lawsuit alleging fraud by Cantor Group V, LLC

** Bankruptcies of auto parts supplier First Brands, car dealership Tricolor spotlight banks' risk controls in opaque credit market, where complex loans have made it harder to gauge exposure

** The KBW Regional Banking index KKRX up 1.2% after Thursday's 6.3% drop