Robinhood Markets and three other online brokers said they resolved disruptions on their platforms Monday after a morning of glitches affected thousands of customers.

Robinhood, which had problems related to equities, options and cryptocurrency trading, said shortly after noon in New York that the issues were fixed. TD Ameritrade Holding Corp., Vanguard Group and Charles Schwab Corp. also reported difficulties, including slowness with websites and mobile apps, that resulted in user complaints.

Clients eager to make trades on the last day of the month were stymied as U.S. markets opened. Speculation online focused on whether some of the problems were related to Apple Inc. and Tesla Inc. stock splits that took effect Monday.

Self-guided traders stuck home during the Covid-19 pandemic have helped give online brokers a boost this year. Second-quarter retail U.S. equity trading volume surged more than 50% from the preceding three-month period, according to Larry Tabb, head of market structure research for Bloomberg Intelligence.

While online brokerages routinely experience brief outages, it’s rarer for several of them to happen simultaneously. Downdetector listed more than 2,900 complaints for Robinhood and more than 7,000 for Ameritrade.

Judy Burns, a U.S. Securities and Exchange Commission spokeswoman, declined to comment, and a spokesperson for the Financial Industry Regulatory Authority didn’t immediately respond to a request for comment.

Trading Surge

Robinhood, which has helped lead gains in online trading this year, is the subject of an investigation by regulators into its handling of an outage in March, Bloomberg News reported Monday.

It wasn’t immediately clear whether the latest disruptions are related. Vanguard said full access to its websites, mobile apps and phones had been restored and apologized to customers. Schwab also said problems that made its website intermittently inaccessible for some clients had been fixed.