GameStop surged as much as 78% on Friday as investors looking to thwart short-sellers piled further into the stock and triggered a trading halt.
The video-game retailer's shares have nearly quadrupled in January after changes to the company's board of directors sparked a massive rally. The upswing intensified this week as short-sellers dumped their bearish positions and an increasingly large crowd of retail traders cheered the stock higher.
The initial surge on Friday triggered a circuit-breaker trade stoppage at about 12:40 p.m. ET. Shares resumed trading soon after, fell slightly, then resumed their climb to new highs.
The fight between shorts and bulls entered a new stage on Thursday after the Citron Research managing partner Andrew Left posted a nearly seven-minute video highlighting five reasons he expected GameStop shares to crash to $20. Left said that he had planned to stream himself explaining his short position but that attempts to hack into his Twitter account forced him to record the video.
The managing partner slammed GameStop's elevated valuation and dependence on physical locations. Left also called out the traders doubling down on the stock, urging them to "know who's on the other side of the trade" and respect their experience in the market.
"This is a failing mall-based retailer," he added. "So the amount of people who are so passionate about putting GameStop higher not based on any fundamentals - it just shows the natural state of the market right now."
Members of the WallStreetBets subreddit were unfazed. The forum, known for its crude markets-based humor and celebration of triple-digit portfolio swings, remained largely bullish on the stock and featured several posts chiding Left for his bearish position.
Commenters urged one another to maintain "diamond hands" and hold their GameStop shares indefinitely. Others called on retail traders to join them to lift the stock even higher.
While it remains to be seen who will win out, some indicators have suggested the bulls' party is ending. The Relative Strength Index for GameStop shares - a measure of the stock's momentum - sat just below 80 following Thursday's 10% climb. Readings above 70 suggest the stock is overbought, and the index hasn't landed below that threshold since January 12.
GameStop closed at $43.03 on Thursday, up roughly 123% year-to-date. The company has two "buy" ratings, two "hold" ratings, and one "sell" rating from analysts.