Shares of GoPro Inc. are on a three-month bender, and much of the blame can be placed on short sellers.

Shares of GoPro GPRO, -1.20% fell another 6.4% to $21.65 in early trade Friday, after slumping 7.8% on Thursday, pushing the stock below its $24 initial public offering price for the first time. The action-camera company’s shares are down 72% over the last year, while the S&P 500 has traded flat.

Most of that decline has happened in the past three months, with the stock plummeting 60% as investors continue to bet the stock is still overvalued. Short interest on the stock has quadrupled over the last year to a record 33.2 million as of Nov. 1, the last time FactSet adjusted its short-interest data, compared with 8.2 million a year ago. High short interest means people are placing bets the stock will fall.

Sungard Astec Analytics, which tracks short interest, named GoPro the No. 1 U.S. “hot stock” for shorts for the second straight week on Wednesday, saying that demand to borrow on the stock has exceeded supply. The second-hottest short stock this week on the Sungard list was Fitbit Inc. FIT, +0.15% , which closed down 8% Thursday.

With such high short interest at this point, “any little indication that things are going south causes concerns about the stock,” said Ben Bajarin, an analyst covering consumer tech for market research company Creative Strategies.

“They’re all sort of looking for the worst-case scenario,” he said.

Michael Pachter, an analyst at Wedbush Securities, said GoPro’s short sellers are confident the stock has meaningful room to fall further, thus the bold activity despite the stock trading a whopping 75% beneath its all-time high of $93.85, reached in October 2014.

“The stock can’t get out of its own way,” Pachter said. “People absolutely detest [it].”

“ “The stock can’t get out of its own way.” ” — Michael Pachter, Wedbush Securities

The stock has been in free-fall since August, with analysts reporting lackluster demand for a new mini-camera, the Hero4 Session. Last week, matters worsened when Polaroid filed suit against GoPro, claiming the Session infringes on its patents.

Shares of GoPro were downgraded to underweight by Piper Jaffray on Oct. 29, with analyst Erinn Murphy, who has a $20 target on the stock, saying that demand appears to be waning. Yet, the stock’s average rating among a poll of 15 analysts remains buy, according to FactSet, while the average target price on the stock is a still-bullish $40.25, according to the poll.

With skeptics declaring GoPro a fad and questioning its ability to innovate and grow its user base, the question at hand is whether the action camera maker will be able to prove the market for its cameras despite slowdowns in sales. It’s a question growing heavier as the holiday season approaches. Last month, GoPro reported disappointing third-quarter sales and an outlook for the holiday quarter that would equate to a roughly 17% year-over-year decline in sales.

Still, enthusiasm among GoPro’s most active users appears strong, said Bajarin, and there remains an untapped opportunity for GoPro’s line of drones and virtual-reality technologies, which have yet to be released but may start to be commercialized in 2016.

“Satisfaction level with [GoPro cameras] is still pretty high for consumers who have them and use them,” Bajarin said. “But Wall Street wants to see sales trends going up, not flat or going down.”