The tricky part with this one isn't the math, it's deciding which market you're even sizing.
Start by clarifying the scope of Google Fi (e.g., US-only or global, consumer vs. business) and then use a top-down or bottom-up approach to estimate the addressable market. Break the market into segments (e.g., individual users, families) and estimate penetration rates based on Google's ecosystem and competitive landscape.
Pro tip: Anchor your estimate to a known metric, such as the number of US mobile subscribers or Google's existing user base, and then apply reasonable assumptions for adoption. This shows you can leverage first principles and Google's strengths.
Ask clarifying questions to define the market: Is it US-only or global? Are we estimating total addressable market (TAM), serviceable addressable market (SAM), or serviceable obtainable market (SOM)? What time frame?
Decide between top-down (start with total mobile subscribers and estimate share) or bottom-up (estimate users per segment and sum). For Google Fi, a top-down approach using US mobile subscribers is often simpler.
Divide the market into relevant segments, such as individual plans, family plans, and business users. Consider factors like price sensitivity, data usage, and willingness to switch carriers.
Estimate what percentage of each segment Google Fi could capture, considering competition (Verizon, AT&T, T-Mobile), Google's brand, and unique features (e.g., seamless switching, Google ecosystem integration).
Multiply segment sizes by adoption rates to get the market size. Sanity check by comparing to known figures (e.g., Google Fi's reported subscriber numbers) and adjust assumptions if needed.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.