Quick answer: The market slide sizes the opportunity. It shows how many customers have the problem, how much they spend, and which segment the company serves first. The classic framework is TAM, SAM, and SOM, but the slide that works is the one that starts with the smallest circle, not the biggest.

TAM, SAM, SOM

  • TAM (Total Addressable Market): the entire market if the product won every possible customer.
  • SAM (Serviceable Addressable Market): the part of the TAM the product can reach with its current model and geography.
  • SOM (Serviceable Obtainable Market): the share the company can realistically win in the early years.

The three numbers are often shown as concentric circles, but the circles are the least useful part of the slide.

Why the big number is the wrong focus

A founder often opens the market slide with a trillion-dollar TAM. The investor reads that as a founder who has no first segment. The investor's question is:

  • Who is the first thousand customers?
  • Where do they live?
  • How much do they pay today?
  • Why are they reachable now?

The market slide should answer those questions before the TAM number.

The defensible sizing approach

Two honest ways to size the market:

1. Top-down. Start with a source (an analyst report, a government dataset, or a public market study), then apply the segment and the reachable share.

2. Bottom-up. Start with the customer count, multiply by the price and the frequency, and build the SOM from the go-to-market.

Bottom-up is more convincing for early-stage startups, because it shows the founder knows the first customer.

The first segment

The slide should name the specific segment that buys first:

  • The industry or the role.
  • The size of the company.
  • The channel where they're found.
  • The reason they buy now.

The first segment is the connection to the problem slide and the go-to-market plan.

How the slide looks

  • A short headline that names the segment.
  • The bottom-up math: customers × price × adoption.
  • The TAM number, sourced, with the source noted.
  • The three-year obtainable share.

What to avoid

  • The giant TAM with no source.
  • The TAM alone, with no SAM or SOM.
  • "Everyone is a customer."
  • A market that grows from a category that doesn't exist yet.
  • A slide that contradicts the product's pricing.

Sources

The market numbers must come from real sources. The common ones are analyst reports, government statistics, industry associations, and the public filings of listed companies. The source goes on the slide. A number without a source is an opinion.

Frequently asked questions

Do I need TAM, SAM, and SOM all three? They frame the slide, but the SOM and the first segment are the ones the investor tests.

Can the market be small? A focused market can be a better pitch than a broad one; the expansion path is the next slide.

What if the market is new and unmeasured? Use the bottom-up math and the proxy markets; don't invent a TAM.

Where does the market slide go? After the problem and the product, before or beside the business model.

Does the market slide change with the deck tool? The layout can be generated, but the numbers are the founder's research.

Start with the first thousand customers. The TAM is a footnote on the first segment, not the headline.

Related guide: the pitch deck guide.