KEY POINTS
  • Data firm Thinknum saw mentions of GameStop start spiking on Reddit days before the stock started rallying again, co-founder Justin Zhen told CNBC.
  • "The volume today has been insane, but we see a huge spike in advance of the run-up of the stock yesterday," Zhen said.
  • Thinknum launched its Reddit-focused dataset after January's GameStop frenzy.

Mentions of GameStop increased on Reddit days before shares of the video-game retailer took off again, according to Justin Zhen, co-founder of Thinknum, a tech firm that compiles alternative data sets for investors.

"In the last 24 hours, we saw the number of occurrences of mentions for GameStop spike. It actually started spiking about four days ago," Zhen said in an interview Thursday on CNBC's "The Exchange."