Facebook Buy-and-Sell Launch: Mission, Goal, Metrics, and Prioritizing a Feed Item Unit

Suppose Facebook has no marketplace product of any kind, and you are the product manager asked to build one: a place where people on Facebook can buy and sell items. The interviewer asks two questions in turn. ### Clarifying Questions - Is the product for local, person-to-person sales of used goods, or also for businesses and items that ship? - Should payment and checkout happen on Facebook in the first version, or do buyers and sellers arrange payment themselves? - Which markets launch first, and does Facebook take any fee at the start? - For Part 2: is the proposed item unit meant for every News Feed user, or only for people who have shown interest in buying or selling? ### Part 1 — Mission, goal and success metrics State the mission of the new product, the goal you would set for its first stage, and the metrics you would use to judge whether it is succeeding. ```hint What makes a buy-and-sell product useful A marketplace is only useful when a buyer finds something worth contacting a seller about. Look for a number that captures both sides meeting, not activity on either side alone. ``` #### What This Part Should Cover - A mission tied to why Facebook in particular is a good home for buying and selling. - A first-stage goal suited to a brand-new two-sided product, and why it comes before revenue. - One north-star metric with supporting supply, demand and trust metrics, plus guardrails for the rest of Facebook. ### Part 2 — Prioritizing a feed unit for items An engineer proposes a feature modeled on People You May Know: a unit in News Feed that shows people items they might want to buy. How would you decide whether, and when, to build it? ```hint Ask what it fixes Before scoring the idea, name which part of the marketplace it would improve, and ask whether that part is the bottleneck at the product's current stage. ``` #### What This Part Should Cover - Which marketplace problem the unit addresses and whether that problem is the current bottleneck. - Its benefits, costs and risks, including the effect on News Feed for people who never buy or sell. - How it ranks against alternatives, and an experiment with a clear decision rule. ### What a Strong Answer Covers - A mission, goal and metric set that are consistent with each other and fit an early-stage marketplace. - Attention to both sides of the market and to liquidity, not just counts of users or listings. - Trust and safety treated as part of success, given scams and prohibited items. - A decision on the engineer's idea that uses the Part 1 goal and metrics rather than instinct. ### Follow-up Questions - Your north-star metric rises, but scam reports per conversation rise too. What do you do? - How would you measure a completed sale when payment and handoff happen off Facebook? - A test of the feed unit lifts buyer messages but lowers time spent on friends' posts. Would you ship it?