Retail traders dump the most stocks in a single day since Covid sell-off

Retail traders dumped the most stocks in a single day since the Covid pandemic, amid Wednesday's massive tech selloff, according to Vanda Research.

Retail investors sold a net $338 million of single stocks on Thursday, with not even an hour into the close, which the market research firm noted was the largest one-day outflow since March 2020 for a group that has been known to buy the dip and keep cash within the market.

The selling comes amid a massive stock market drawdown as traders rotated out of technology. On Thursday, the Dow Jones Industrial Average plummeted 1,800 points, effectively erasing any post-midterm bump, while the Nasdaq Composite dropped into a correction.

"On a typical sell-off, retail buy the dip," read a note from the firm. "Today, that bid has effectively disappeared from individual names."

The firm noted that what buying remained has been concentrated in leveraged vehicles such as the ProShares UltraPro QQQ (TQQQ), which delivers three times the performance in the Nasdaq-100 index, and the Direxion Daily Semiconductor Bull 3X Shares (SOXL), which is supposed to track moves in semiconductors.

"This looks like a rare buyers' strike colliding with forced selling," read the note.

— CNBC's Nick Wells contributed to this story.