Robinhood • $1 billion
When stock markets cratered at the start of the Covid crisis, investing app Robinhood suffered debilitating outages, leaving customers unable to trade on several volatile days. But the brokerage thrived later in 2020 as millions of novice traders plowed their stimulus checks into stocks and crypto. Robinhood was at the center of the GameStop fiasco of January and February as margin calls depleted its cash and forced a $3.4 billion capital raise. Now both billionaires are looking to tap into the roaring stock market they helped fuel.