Vanity metrics vs. liquidity metrics
The most common mistake marketplace founders make at seed stage is optimising for top-line metrics that look good but prove little. Total listings, total signups, gross merchandise value and monthly active users all tell you that people have arrived. They do not tell you whether people can find what they need, whether transactions complete or whether users come back.
Liquidity metrics are different. They measure whether the marketplace works for a specific user at a specific moment. Time to first match, search-to-transaction rate, fill rate by category, supplier response time and buyer repeat rate all test the core loop. If these metrics are healthy, the marketplace is working even if total numbers are small. If these metrics are poor, growth is just amplifying a broken experience.
Time to first match
How long does it take a new user to find something useful? In a local classifieds site, this might be the time between a first search and a first completed transaction. In a B2B platform, it might be the time between a first enquiry and a first signed contract.
The shorter this period, the more likely the user is to return. Early classifieds platforms that concentrated supply in dense urban markets found that a flatshare search could return viable results within minutes. That speed turned a first-time visitor into a repeat user. If your time to first match is measured in weeks, the network is not yet liquid enough for the segment you are serving.
Search failure rate
How often does a user search and find nothing relevant? This is one of the most under-measured metrics in early marketplaces because it is invisible: you only see the searches that happen, not the users who left without searching because they expected nothing.
A healthy marketplace at seed stage might still have significant search failure in under-served categories, but it should have very low failure in its primary use case. If your core category has a high failure rate, you are spreading too thin. Narrow the segment.
Supplier return rate
Does supply come back? In a marketplace where supply is one-time, like a second-hand good, this metric is less relevant. But in a marketplace where supply is a service provider, a host, a landlord or a recurring seller, the supplier return rate tells you whether the platform is generating enough demand to keep suppliers listing.
If your childcare providers post once and do not return, the demand side is not generating enough matches. If your hosts list once and get bookings, they will return. This metric is a direct proxy for whether the marketplace is delivering value to both sides.
Repeat transaction rate
The strongest signal that a marketplace has product-market fit is not first-time use. It is repeat use. What percentage of buyers make a second transaction within a defined period? What percentage of sellers list again?
Repeat transactions are the compounding engine of marketplace value. A user who returns is worth many times more than a user who leaves. At seed stage, even a small cohort of repeat users is more meaningful than a large number of one-time visitors.
Track this by segment. If repeat use is high in your primary category but low in secondary categories, you know where to double down. If it is low everywhere, the core loop is not yet working.
Net revenue per transaction
At seed stage, revenue per transaction may be zero or near zero if the marketplace is subsidising one or both sides. That is acceptable if the unit economics path is clear. What matters is whether you can articulate the path from current monetisation to sustainable take rates.
For founders building marketplaces, the typical monetisation path follows a proven sequence: free consumer listings, then paid job listings, then premium placement, then broader business services. Each stage is proven before the next is introduced, as platforms like Gumtree demonstrated. The same discipline applies today: prove that users will pay for a specific value-add before building a revenue model around it.
The metrics we ask about
When we evaluate a seed-stage marketplace, the first metrics we want to understand are:
Liquidity: What percentage of searches return at least one relevant result in your primary category?
Match quality: What percentage of initial contacts result in a completed transaction?
Repeat behaviour: What percentage of your users transact more than once in 90 days?
Supplier health: Do your supply-side providers list again after their first transaction?
Concentration: How much of your activity depends on a single category or geography? Concentration is fine at seed stage, as long as you can articulate the path to expansion.
If you are tracking these metrics and can explain what they mean for your market, we would like to hear from you.