Facebook Buy and Sell Groups: Why Listing Supply Stalls While Buyer Engagement Climbs

You are the product manager for Buy and Sell Groups on Facebook, the groups where members post items for sale and other members browse them, comment and message the seller. Engagement with listings in these groups keeps rising, but the total number of listings has stopped growing and is now flat. What could explain this, and how would you work out which explanation is right? ```hint Separate buyers from sellers Engagement mostly reflects buyers, while the listing count reflects sellers. Break the listing count into factors that multiply together and find which factor stopped growing before you start listing causes. ``` ### Clarifying Questions - Which engagement metric is rising (views, comments, messages to sellers, saves), and is it a total or a per-listing figure? - Does "listings" mean new listings created each week or active listings live at any moment? - How long has the count been flat, and did it level off suddenly or gradually? - Does the pattern hold across countries, item categories and group types, and did anything launch or change around the time it started? ### What a Strong Answer Covers - Precise definitions of both metrics and a check that the data and logging are sound before diagnosing - A decomposition of listing volume and a segmentation that narrows where the plateau comes from - Hypotheses on both sides of the marketplace, internal and external, including ways rising engagement could itself hold listings flat - A prioritized plan to confirm causes with data and experiments, plus the metric and guardrails for any fix - A judgment on whether the pattern is a problem and what it means for marketplace health ### Follow-up Questions - The data shows sellers moved their listings to Facebook Marketplace instead of stopping. Is that a problem for you, and what would you do? - If engagement per listing keeps rising because supply is scarce, what happens to buyers over time, and which metric would warn you first? - What single goal metric would you set for Buy and Sell Groups, and why?