Share of Market is the portion of the serviceable addressable market a product or solution actually captures — its realized share, after competition and the customer's option to do nothing. It is BRI's definition of the SOM in the TAM/SAM/SOM hierarchy (the acronym is sometimes written out as serviceable obtainable market). Of the three figures, it is the one most often inflated: a model that ignores switching cost and the status-quo, do-nothing alternative overstates how much of the reachable market a new offering will really win.
Share of Market sits in the Financial Logic dimension of the BRI Strategy Framework as the final filter in the TAM-to-SAM-to-Share-of-Market funnel; multiplied by pricing, it produces the revenue forecast, and it feeds the Viability judgment. In Growth Forge® Software the Market Sizing tool computes it as a market-share filter applied to SAM and turns it into a revenue forecast. For the full treatment, see the Market Sizing pillar at /supporting/market-sizing. Related Terminology Index entries: Total Addressable Market; Serviceable Addressable Market; Market Sizing; Target Markets; Competing Alternatives; Viability.
