Driven by online forums such as Reddit's WallStreetBets, the phenomenon has raised concerns in recent weeks among short-sellers and regulators alike.

Here are some of the stocks involved in the initial frenzy and how they have fared since, as of Tuesday's close:

** Shares of GameStop - which had been heavily touted on Reddit's WallStreetBets - rose by as much as 2,460% on the year to a high of $482.25 in January, as some institutions that had bet on declines in the stock were forced to unwind their positions amid a flood of buying. The stock pared most of that rally earlier this month but remains 527% higher on the year.

** AMC Entertainment Holdings' stock surged after the company said bankruptcy talks were "completely off the table." At the rally's apex, its shares touched $20.36, an 860% jump from Dec. 31. Tuesday's closing price put the stock up 321% in 2021.

** Shares of Canada's Blackberry rallied as much as 334% but had pared that to a 58% year-to-date advance as of Tuesday. The company announced late last month that it was expanding its partnership with China-based search platform Baidu Inc

** At one point, home furnishings retailer Bed Bath & Beyond's had jumped by 204% year-to-date, but its advance has since cooled to 56%.

** Pharmaceutical firm CEL-SCI Corp shares hit a zenith of $40.77, a 247% advance on the year, a gain that has since shrunk to 59%.

** Finland-based Nokia joined the short squeeze stampede, at one point touching a 150% year-to-date gain at $9.79 per share. That advance was recently a more modest 3%.

** Consumer electronics company Koss Corp was also caught in the mania, soaring by 3,605% at one point. The stock is up 371% so far in 2021.

** Shares of cannabis companies - which have already notched big rallies on hopes of decriminalization under U.S. President Joe Biden - have been among the latest to experience wild fluctuations. Weekly volumes in cannabis stock options soared to an all-time high by Thursday, according to CBOE Global Markets, and U.S.-listed shares of Tilray Inc and Aphria Inc, along with Sundial Growers, were at one point up on the year by 711%, 367% and 736%, respectively. As of Tuesday's close, they had gained between 174% and 214%.

** On Tuesday, Mortgage dealers UWM Holdings Corp and Rocket Companies gained 71% and 20%, respectively, despite a slew of recently canceled initial public offerings in the sector in recent weeks, which point to fears the housing market may have reached a peak. So far today, UWM Holdings is up 8.5%, while Rocket Companies is down 27.9%

(Reporting by Stephen Culp; editing by Barbara Lewis)