In almost every out-licensing or investor presentation we see, there is likely a slide that shows the “Total Addressable Market” (TAM). And, it is always a very large number. The message that is being conveyed is that if the TAM is large, then the opportunity is large, and hence you (prospective Licensee or Investor) should license or invest.
I suppose TAM can be useful in other industries, such as consumer products or e-commerce. But in our world, TAM is a profoundly misleading metric.
No licensee selects a drug candidate for licensing based on TAM. No experienced biotechnology investor commits capital on the basis of TAM. Yet many early-stage companies continue to highlight TAM as the centerpiece of their opportunity story.
Why?
Why TAM Sounds Convincing
TAM is appealing because it is simple and straightforward. It is basically the total theoretical sales potential if a product captured 100 percent of the market. Similar metrics, such as Serviceable Available Market (SAM) and Serviceable Obtainable Market (SOM), attempt to narrow this further. But, in practice, biotechnology entrepreneurs often show TAM because it produces large, headline-grabbing numbers.
Consider the familiar pitch line: “The TAM for Obesity is $700 billion. If we capture just one percent, that is $7 billion in Sales!” The math is simple. It suggests that success does not require market dominance, but only a sliver of an enormous pie. To naïve investors less familiar with the nuances of drug development, this can sound compelling.
Moreover, TAM aligns with a cultural preference for scale. Bigger “sounds” better. A large TAM implies a blockbuster drug, and everyone likes a blockbuster. The temptation to anchor on TAM is, to some degree, understandable.
Why TAM Fails in Biotech
Scientific and clinical risk. A drug candidate in Phase I has less than a 10 percent chance of ultimately reaching the market. A vast TAM does not increase those odds. Just look at diseases such as Alzheimer’s, which has an enormous TAM and very few successful candidates.
Regulatory hurdles. Approval pathways vary by indication. A company developing a pan-oncology therapy may quote a TAM across dozens of tumor types, but regulators approve drugs one indication at a time. The effective market is therefore a fraction of TAM until many years of development expand the label.
Commercial realities. Even with approval, adoption is not automatic. Physicians follow treatment algorithms. Payers erect access barriers. Health technology assessment bodies impose pricing limits. The result is that the serviceable market is far smaller than TAM, and capturing even a modest share requires resources that most early-stage companies cannot deploy.
Because of these and other factors, licensees do not evaluate opportunities on TAM. They ask instead: Does this asset differentiate clinically? What is the probability of technical and regulatory success? What are the development risks? How does it fit with our portfolio strategy? How does this opportunity compare to others we are evaluating?
Similarly, investors do not value companies on TAM but on risk, valuation, capital efficiency, and realistic exit potential.
Examples of TAM Misuse
Obesity. Stifel estimates that the obesity TAM could be ~$700 billion, or roughly the size of the entire US Medicaid budget. Few markets are larger. Global obesity prevalence continues to rise, and the medical consequences, such as diabetes, cardiovascular disease, and fatty liver disease, create incalculable downstream costs. Yet until recently, most obesity drug programs failed commercially. Safety concerns, modest efficacy, and reimbursement hurdles made licensing partners wary. Only with the advent of GLP-1 agonists did the field finally break through. The TAM was always there, but it did not matter until clinical data and payer acceptance aligned.
Now we have the opposite problem. We have ~360 candidates in clinical development for obesity. Most of these will fail in clinical development. Companies such as Roche are terminating otherwise successful programs (CT-173) in the space because it was insufficiently competitive. Roche is not exiting obesity entirely. Far from it. Roche still has multiple candidates in development for obesity. But it shows that companies are prudent about what they advance, irrespective of the TAM.
Oncology. Companies sometime extrapolate TAM across multiple tumor types. For example, “Our therapy targets a pathway active in 12 cancers, representing a $40 billion TAM.” But regulatory approval requires indication-by-indication demonstration of efficacy over standard of care. Commercial adoption similarly proceeds indication by indication. In reality, the initial market might be a single tumor type worth a few hundred million dollars, not tens of billions.
Rare diseases. Here we have a bit of a paradox. Many rare diseases have a TAM of less than $1 billion. By TAM logic, they should be unattractive. Yet orphan drug incentives, premium pricing, and relatively low commercialization hurdles make them highly attractive licensing and investment opportunities. The small TAM is irrelevant compared to the compelling economics of niche markets.
What Licensees and Investors Actually Care About
If TAM is not the compass, what guides Licensees and Investors?
Strategic fit. Pharmaceutical companies license assets that complement existing pipelines, leverage commercial infrastructure, or strengthen therapeutic area leadership. Even a lucrative TAM will not justify a deal if the asset lies outside strategic focus.
Clinical differentiation. At the end of the day, data drives decisions. Licensees and investors want evidence that a candidate is meaningfully better than the standard of care in a clinically relevant population.
Treatment Evolution. How will this candidate compete against tomorrow’s standard of care at the time of launch? Licensees think about this question routinely, and it is a difficult one to answer precisely. But even a paper exercise looking at the pipeline and scenarios is better than a random TAM number from the Internet.
Competitive landscape. An attractive TAM often draws many players. If five other companies have Phase II assets in the same indication, the odds of achieving differentiation shrink, as we are seeing in the Obesity market.
Payer environment. Decision-makers focus on the likelihood of approval and the probability of reimbursement. In markets such as oncology, payer scrutiny has become intense. Numerous therapies priced aggressively in the US are approved but not reimbursed ex-US. Without clear evidence of superior outcomes justifying the pricing, adoption may be limited regardless of TAM.
Development Potential. Could the candidate be developed in multiple indications? Across multiple therapeutic areas? Do the data support this “platform in a box” potential?
Risks. What are the risks (safety, efficacy, CMC, others), and how can they be mitigated?
Conclusion: Why the TAM Sham Matters
The reliance on TAM has real consequences. Companies that emphasize TAM risk misaligning their strategy with the criteria that matter to partners and investors. They risk raising capital on unrealistic premises, only to disappoint when sophisticated stakeholders dismiss TAM as irrelevant.
The tragedy is that worthy programs may be overlooked because entrepreneurs waste precious time selling TAM rather than demonstrating value in terms that decision-makers respect. Conversely, naïve investors may be seduced by TAM slides, only to discover later that the science and economics do not hold, wasting precious capital in the process.
What do we recommend?
Ditch the TAM pitch.
Biotechnology is not consumer software or e-commerce. Success depends not on capturing a sliver of a massive market but on navigating scientific risk, regulatory complexity, payer dynamics, and clinical differentiation.
For founders, executives, and investors alike, recognizing the TAM Sham is the first step. Replacing the TAM slides with evidence-driven credibility is the way forward.