Elon Musk's Twitter investment sparks a rush of retail investors into the stock

Tesla CEO Elon Musk arrives on the red carpet for the Axel Springer Award 2020 in Berlin, Germany, on Dec. 1, 2020.
Britta Pedersen | Getty Images

Elon Musk's surprising move to take a big stake in Twitter and become its board member inspired retail investors to pile into the social media stock like never before.