During the day-trading craze that erupted amid the Covid-19 pandemic’s lockdowns, market professionals repeatedly warned a new flock of Reddit-reading, Robinhood-using retail investors that equity options were risky, and that bold bets in that market could end badly. It turns out their caution was spot on.

Day-traders managed to lose more than $1 billion during the bull market, with the bill climbing to $5 billion when the cost of doing business with market-makers is factored in, according to Svetlana Bryzgalova, Anna Pavlova and Taisiya Sikorskaya of the London Business School. The three researchers joined the “What Goes Up” podcast to talk about the findings of their study, and discuss what retail traders need to know about options trading.