On Boston Public Radio Friday, Emily Rooney described how a group of people organized by social media used a Wall Street tactic to redistribute millions of dollars away from hedge funds, and into the pockets of amateur traders by buying up stock from a dying retailer, GameStop.

“This was an insurrection by a group of people who said we’re mad as hell and we’re not going to take it anymore, and they beat Wall Street at their own game and now Wall Street is really really mad,” she said.

How did they do it? BPR producer Zoe Mathews checked in with MIT economist Jon Gruber for a primer, ahead of his definitive explainer next week on the show.