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TAM / SAM / SOM

Total Addressable Market / Serviceable Addressable Market / Serviceable Obtainable Market. A framework for thinking about market size — often misused as a marketing tool, but useful when applied skeptically.

The definitions

  • TAM (Total Addressable Market): the total demand for a product or service category, assuming 100% market share and ideal conditions
  • SAM (Serviceable Addressable Market): the portion of TAM the firm can realistically address with current product, distribution, geography
  • SOM (Serviceable Obtainable Market): the portion of SAM the firm can realistically capture given competition and execution capacity

Why this matters for deep value

The deep-value angle is the inverse of the typical growth angle:

Growth use: "TAM is $500B; if we capture 5%, that's $25B revenue at maturity."

Deep-value use: "Implied price requires capturing $25B revenue; the realistic SOM is much smaller; therefore the price is high."

The same framework, applied with skepticism, deflates the optimism that high TAM numbers can support.

How to interrogate a TAM claim

Test 1 — How was TAM derived?

  • Bottom-up (units × ASP)
  • Top-down (% of GDP, IT spending, healthcare expenditure)
  • Bottoms-up from unit-economic projections

Bottom-up TAMs are usually more reliable than top-down "% of large category" ones.

Test 2 — Is TAM today or TAM at maturity?

A "TAM" of $500B that requires 10-15 years of expansion is different from a TAM of $500B today. The discount rate applied to "future TAM" matters enormously.

Test 3 — Penetration realism

What share of TAM has actually been penetrated by today's leaders? What is the realistic terminal share?

Most "TAM" claims for narrative-driven thematic sectors imply unrealistic terminal shares for individual companies. The market doesn't usually concentrate to 30-50% share for a leader; the typical leader captures 5-15%.

Test 4 — Base rate of TAM realization

Across historical examples (PCs, smartphones, SaaS waves, internet adoption), what share of the early TAM projections actually materialized? Typically:

  • Within 5 years: 30-50% of projected TAM
  • Within 10 years: 60-90% of projected TAM
  • Some segments overshoot expectations; many fall short

Adjust accordingly.

Test 5 — Competitive dynamics

Even when TAM is real, the competitive dynamics shape who captures it. Multi-vendor / multi-homing markets prevent any single leader from dominating; winner-take-all markets concentrate.

What good TAM analysis looks like

For a thesis involving market sizing:

  1. Bottom-up TAM with the underlying unit and ASP assumptions stated
  2. SAM with explicit exclusions (geographies, channels, customer segments)
  3. SOM with realistic share projections, justified by competitor base rates
  4. Time path — when does TAM penetrate, with what curve?
  5. Sensitivity to penetration timing
  6. Comparison to comparable historical adoption curves

What bad TAM analysis looks like

  • "$500B market" with no breakdown
  • "1% share = X revenue" arithmetic without justifying the 1%
  • TAM that grows because of an assumed adoption that isn't sourced
  • Multi-decade TAM with no discount applied
  • Multi-product TAM stacked without market overlap analysis

Deep-value applications

Skepticism on narrative-driven TAMs

When markets fall in love with a theme, TAM claims expand dramatically. The skeptical investor models with conservative TAM and realistic SOM, often finding the implied prices unjustifiable.

Identifying under-priced TAM

Sometimes the inverse — a real TAM exists but is unrecognized by the market. Often in B2B / specialty industries where TAM isn't a publicly-discussed metric.

Capacity vs. demand framing

For mature industries, the "TAM" is essentially current consumption. The deep-value question shifts from "can we grow into a bigger TAM" to "can we earn returns on current TAM."

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