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Two-Sided Marketplace Liquidity & Scale-Trigger Thresholds

A marketplace's version of PMF is not one number — it has to work on both sides simultaneously, and the two sides are driven by different levers:

• Demand-side value is largely a function of selection and conversion (is there enough supply to convert a demand-side visit into a completed transaction).
• Supply-side value is largely a function of volume — whether the transaction volume a supplier gets is enough to justify staying on the marketplace.

Evaluate these separately rather than reaching for one unified PMF metric.

Scale-trigger thresholds. Once you have data, define a custom supply-side retention threshold specific to your marketplace — GrubHub's was restaurants hitting 'two orders a day' within four months of onboarding. Alongside that, watch for supply density crossing a level that makes demand-side acquisition and retention scale efficiently on their own. Casey's rough rule of thumb: around 40% conversion/retention on both sides is the point where network effects start doing the acquisition work for you, rather than the company having to fuel every transaction with paid acquisition or subsidy.

Related: Matching Rate as Core Marketplace Metric, Demand-First vs. Supply-First Marketplace Launch Strategy.

Из тем: Growth, PMF, and Business Model Design