It was an alarming series of breakdowns that baffled traders: as two of the most popular stocks split at the start of the week, thousands of U.S. retail investors couldn’t use their brokerage accounts.
Increased trading precipitated by Apple Inc. and Tesla Inc. share splits contributed to problems at Robinhood Markets and Charles Schwab Corp. when markets opened in New York on Monday, according to people familiar with the matter. Retail clients of Vanguard Group, TD Ameritrade Holding Corp.and Fidelity Investments also experienced disruptions.
Read more: Robinhood, Schwab and Other Brokers Resolve Online Glitches
While most of the...