TransMedics Stock Is Up 104% Over the Last Year: Is It Too Late to Buy for 2026?

Shares of transformational organ transplant company TransMedics Group (NASDAQ: TMDX) are up 104% over the last year as the company continues to become the clear leader in its niche. While it is easy for investors to feel like they missed their opportunity to buy a stock once it doubles, The Motley Fool's co-founder, David Gardner -- and his six traits of a Rule Breaker stock -- say the exact opposite is true. Strong past price appreciation is one of the traits that helps investors find the most promising growth stocks on the market, which I believe TransMedics will continue to be. Best yet for investors: This isn't the only Rule Breaker trait that TransMedics is home to.

TransMedics: Revolutionizing the organ transplant industry

TransMedics offers a turnkey, end-to-end offering for organ transplants through its Organ Care System (OCS) and its National OCS Program (NOP). Its OCS is a next-gen array of solutions that "replicate many aspects of the organ's natural living and functioning environment outside of the human body," keeping the donated organs much healthier than traditional ice storage methods. Meanwhile, TransMedics' NOP helps streamline operations on the clinical side, while the company's logistics network of 22 aircraft and 18 hubs across the U.S. provides expedited transportation for organs. Powered by these new innovative solutions, TransMedics looks like a true Rule Breaker.

1. Top dog and first mover in an important, emerging industry

TransMedics' leading-edge OCS makes it a first mover in its industry, where it holds roughly a 20% market share in U.S. transplants for livers, hearts, and lungs. While the organ donation industry isn't an "emerging" market per se, there is an immense opportunity for optimization. Only 20% of hearts, 24% of lungs, and 61% of livers donated in the U.S. get utilized.

As TransMedics' OCS and NOP steadily push these figures higher, the company is essentially turning the industry into an emerging one. Furthermore, donations after circulatory death -- which are typically vastly underutilized compared to donations after brain death -- have jumped sixfold since 2017, highlighting that the company's capabilities are fueling growth.

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2. Sustainable competitive advantage

Powered by new generations of its OCS for livers, hearts, lungs, and possibly kidneys, TransMedics and its NOP network are hard for any single company to replicate. This vertical integration from research and development on new iterations of its products, all the way down to providing the logistics to use its products, makes the company's moat quite wide.

3. Strong past price appreciation

Not only has TransMedics doubled over the last year, the stock is an eight-bagger since its 2019 initial public offering. While its share price will likely remain volatile thanks to the company's high sales growth rates -- 32% in its latest quarter -- TransMedics' stock has consistently reached new highs.

4. Good management and smart backing

TransMedics is founder-led by its Chief Executive Officer, Dr. Waleed Hassanein, who has been working on organ donation products since the early 1990s while he was at Georgetown University. That said, Hassanein owns only 2% of the company's outstanding shares, so investors may not want to give too much weight to insider holdings. Furthermore, TransMedics has a very weak 3.2-star rating on Comparably, and only 44% of employees approve of the CEO, so these low culture scores are worth monitoring for prospective investors.

5. Strong consumer appeal

TransMedics doesn't have a strong consumer brand appeal, but its products serve a greater good, making it hard to oppose the company's continued success. In addition to saving more lives than ever before by disrupting traditional ice storage donations, the company alleviates many headaches for its healthcare customers by streamlining the entire organ donation process.

6. "Overvalued" according to the financial media

A simple web search will yield an array of negative opinions on TransMedics stock, most stemming from its "high" valuations. The company even faced a short report early in 2025, but it has since more than doubled its share price. Perhaps the strongest signal that the market thinks TransMedics' stock remains overvalued is the hefty 25% of its float that is held short. However, while the market views the premium on the company's stock as a reason to short it, Rule Breaker proponents argue that the company's leadership position and strong growth rates warrant it. This "expensive" valuation is a feature, not a bug.

Pricey but promising

Trading at 56 times forward earnings, TransMedics is certainly more "expensive" than the broader market. However, this valuation only views things through a short-term lens. As TransMedics builds out its NOP in Italy, tests its next-gen OCS heart and lung programs, launches an OCS kidney clinical trial, and continues expanding internationally beyond the U.S. and Italy, it could easily outgrow this "overvalued" price tag.

Josh Kohn-Lindquist has positions in TransMedics Group. The Motley Fool has positions in and recommends TransMedics Group. The Motley Fool has a disclosure policy.