A spike in individual investing this year has buoyed the entire brokerage industry. Retail equity orders accounted for 20% of U.S. stock trading in the past quarter, up more than five percentage points from the prior year. But as much as the boom in stock trading by individuals has been a hallmark of this year, so has service disruptions at the online brokerages. What’s more, customers have also reported hacks into their brokerage accounts.