Addressable market
An estimate of the total revenue opportunity available to a company. TAM (Total Addressable Market) covers the full market; SAM (Serviceable Addressable Market) is the accessible portion; SOM (Serviceable Obtainable Market) is the realistically achievable share.
In practice
The TAM / SAM / SOM distinction is essential for calibrating ambition and funding needs. A TAM of 10 billion euros is of little use if the SAM is 200 million and the 5-year SOM is 10 million. Investors want a broad enough TAM to justify the ambition, a specific SAM to validate feasibility, and a SOM that reflects a realistic understanding of competition. An unsupported TAM estimate signals weak analytical rigour.