Key TakeawaysCharles Schwab beat first-quarter profit and revenue estimates as the runup in U.S. equities during the quarter fueled its business.The discount brokerage and financial advisory firm said investor sentiment "improved noticeably" during the first three months of the year.Schwab's brokerage accounts, trading volume, and margin balances all increased. Shares of Charles Schwab (SCHW) rose 4% in early trading Monday after the discount brokerage and financial advisory firm reported better-than-expect ...