Episode 30: The Moderna Bear Case with Seedy19
In our first guest interview on FOMO Investing, we speak with biotech investor and Substack writer Seedy19 about his controversial bearish thesis on Moderna.
Moderna's personalized cancer vaccine has generated considerable excitement, with investors increasingly treating the company as a potential breakthrough platform in oncology. But how much of that promise is already reflected in the stock price?
Seedy walks us through his investment process, the science behind Moderna's cancer vaccine, and why he believes the market is extrapolating too much from promising results in melanoma. We discuss the differences between clinical success and commercial success, the challenges of manufacturing personalized treatments at scale, Moderna's economics-sharing arrangement with Merck, and the assumptions embedded in its valuation.
We also explore the role of momentum, AI enthusiasm, and investor psychology in driving biotech valuations.
The conversation becomes particularly interesting when we turn to the challenges of short selling. Seedy speaks candidly about his own losses, the difficulty of being early, and what evidence would cause him to reconsider his thesis.
Topics discussed:
- Seedy19's process for identifying asymmetric opportunities in biotech
- Why promising clinical results don't necessarily translate into attractive investments
- Moderna's melanoma results and the prospects for other cancer indications
- The economics of personalized cancer vaccines and the Merck partnership
- The role of AI narratives, momentum, and FOMO in Moderna's valuation
- What would invalidate Seedy19's bearish thesis
- Position sizing, short squeezes, and the difference between being right and making money
Recorded October 13, 2026, ahead of the anticipated additional melanoma data. Opinions, market prices, and expectations reflect information available at the time of recording.
Disclaimer: This discussion is for informational purposes only and does not constitute investment advice. Participants may hold positions in securities discussed.
