Two of the most-hyped industries in recent years—artificial intelligence (AI) and green hydrogen energy—have each produced a number of breakout star stocks, the result of widespread investor enthusiasm for the transformational potential of new technologies. However, even within a highly popular industry not every company can succeed all the time, and one company in each of those two spaces has emerged as a contender for most-shorted stock as of mid-March 2025.
SoundHound AI (NASDAQ:SOUN) and Plug Power (NASDAQ:PLUG) have each experienced massive spikes in popularity and share price in recent years—SoundHound late in 2024 and early into the new year and Plug Power in 2021. Now, these firms have attracted a high degree of short interest among investors, who are banking on them to continue to fall in price into the future. But is it time to join the bears or take a contrarian, bullish view of these two companies while they each trade at levels far below their peaks?
1. SoundHound’s Short Interest Rises 19%, Though Revenue Growth and Market Expansion Impress
Short interest in voice AI platform developer SoundHound has surged in recent weeks, climbing by about 19% in the month leading to March 14, 2025. As of that date, the short percent of float is more than 34%. Shares of SoundHound plunged early in the year alongside news that chip leader NVIDIA (NASDAQ:NVDA) recently liquidated its entire position of under 2 million shares, although it could be that the second-largest company by market capitalization was simply looking to align its investments with its core offerings.
Plus, despite SoundHound’s recent price drop, it may still raise bearish investors’ valuation concerns based on its price-to-sales ratio of 48.0. Finally, bears can point to SoundHound’s recent history of fairly significant share dilution—the share count increased by about 50% over the last year—as a potential barrier to future growth.
On the other hand, SoundHound bulls can cite the company’s excellent growth trajectory, including fourth-quarter revenue that came in just over double the prior-year quarter’s and 85% year-over-year (YoY) revenue improvement compared to 2023. The company also recently raised its full-year 2025 revenue guidance to be in the range of $157 to $177 million, which would mean another year of revenue roughly doubling (at least).
SoundHound has seen successful penetration of a variety of markets, including restaurants, healthcare, insurance, automotive, and more. Though competition remains stiff, SoundHound’s customer base and brand recognition are strong and continuing to grow.
2. Plug Power Sees Short Interest Drop, Focuses on Cost Savings and Green Hydrogen Amid Market Challenges
Hydrogen fuel cell developer Plug Power has actually seen a slight drop in short interest in the last month, although the short percent of float remains high at 31.5% as of March 14, 2025. Domestic and international policy changes and geopolitical turmoil have slowed the global transition to clean hydrogen, and Plug Power now sees the data center backup power generation market impacting its business only by 2028 or 2029. Revenue was hit hard in the latest quarter by production delays and other factors, charges related to asset impairments and bad debt mounted, and overall costs remain high.
In early March 2025, Plug Power announced plans to reduce costs through staff reductions, operations consolidation, and other measures expected to generate between $150 million and $200 million in annualized cost savings. The company’s customer demand still outpaces its production capacity, but in January it received Department of Energy (DoE) approval for its new Limestone plant in Texas.
Plug Power is also shifting part of its focus to encompass customers interested in transitioning from grey hydrogen (created using fossil fuels) to green hydrogen, which the company says is significantly simpler than other portions of the hydrogen fuel cell market. The company has also managed to improve service and hydrogen margins relative to 2023.
Between these two firms, SoundHound may have the immediate advantage for bullish investors because of its accelerating top-line growth. However, those willing to wait out challenges may see a wholesale shift toward green hydrogen that could benefit Plug Power over the long term. Both companies continue to face significant headwinds, though, so investor caution is advised in either case.