Robinhood’s Meteoric Rise Feels the Pull of Wall Street Physics

Robinhood Markets’ emergency ban on trading eight stocks this week ignited rage across the political spectrum, swiftly drew state and federal scrutiny and sent furious customers into the arms of competitors.

That was Thursday. By Friday afternoon, it was limiting purchases of shares in 23 companies. Soon, it was about 50.

A drama that began with a quirky jump in GameStop Corp.’s shares this month has grown into a full-blown rebellion of retail investors against Wall Street’s status quo and left Robinhood, long their beloved brokerage, caught between customers and the cold demands of finance’s gatekeepers. Mounting ...