It seems meme stocks are back, and this time, the latest craze was sparked—somewhat accidentally—by a Canadian hedge fund manager named Eric Jackson.

Day traders flooded into the stock, sending institutional investors who were betting against it scrambling to buy back shares they had dumped. Which sent prices soaring even higher. “Up almost 40%,” Swartz said. Rinse and repeat with the other oddball stocks the internet latched on to this week.

Social media buzzed with excitement on Monday as some beaten-down stocks that retail traders have been buying began to soar. Kohl's, Opendoor Technologies, Krispy Kreme and Rocket Cos. were among the names that posted outsized swings throughout the week.