The myth of volume in prediction markets: where liquidity really is

Prediction markets now show the kind of headline volume that makes them look mainstream. But volume is not the same thing as liquidity. Liquidity is what you can trade now, at a fair price, without paying hidden costs. A platform can clear huge monthly notional and still have thousands of contracts where you are effectively trading against noise, bots, or your own impatience. That gap is where most new traders get hurt.

This post is a practical guide to reading liquidity in prediction markets. We will use two simple ideas: depth matters more than volume, and a third outcome changes how you think about uncertainty. We will also walk through a worked example and end with a checklist you can apply before your next trade.

Liquidity 101: volume, depth, and spread (in one minute)

• Volume is how much traded in the past.
• Depth is how much you can trade right now near the current price.
• Spread is the price you pay for immediacy.

If you take only one thing from this post, take this: depth and spread describe your execution risk. Volume rarely does.

First: what a prediction market price actually represents

At a high level, prediction markets let participants trade event-linked contracts. CoinGecko puts it plainly: “Prediction markets let users bet on the outcome of ongoing and future events using cryptocurrency.” (CoinGecko)

Mechanically, markets turn beliefs into prices. CoinGecko explains that the price “represents the market’s estimate of the probability of the event occurring.” (CoinGecko) Phemex adds the familiar shorthand: “A contract priced at $0.20 is commonly interpreted as a 20% chance.” (Phemex Academy)

That interpretation is useful, but it is not magic. It only holds when the market is liquid enough that prices respond to new information, not to one impatient trade.

Why headline volume misleads

Many traders anchor on the biggest number they can find: “monthly volume”. It is easy to see why. Pew Research notes: “As of April, monthly trading volume on the two largest prediction markets – Polymarket and Kalshi – had reached nearly $24 billion.” (Pew Research Center)

That is a real milestone. But it does not tell you whether the specific contract you want to trade has:

• tight spreads,
• stable depth around the mid price,
• enough two-sided interest to keep you honest,
• and enough diversity of participants to reduce manipulation risk.

Platform-wide volume can concentrate in a handful of headline events. The long tail can be effectively empty.

A quick Yes / No / Maybe refresher (keep it short)

Most prediction venues structure contracts as Yes/No shares. Phemex describes the common binary pattern: “The market creates two outcome tokens or shares: one tied to YES, one tied to NO.” (Phemex Academy)

Oddup adds a third option: Maybe. The point is not “more choices”. The point is better modelling of uncertainty. The third leg changes how you hedge when the true outcome set is messy, when resolution is contested, or when your edge is in timing rather than direction.

In Oddup’s design, Maybe wins a fixed share of the pool reserve. That is a structural allocation, not a guarantee of profit per bet. Treat it like a different payoff profile, not a free lunch.

The five liquidity signals that matter more than volume

1) Spread: your first hidden cost

Spread is the simplest indicator. In a clean, active contract, the best bid and best ask sit close together. In a thin contract, you will see a gap that looks small until you try to size up.

Practical rule: if your expected edge is smaller than the spread, you are already behind.

2) Depth: what you can actually buy or sell

Depth answers a simple question: how much can you trade near the current price?

Volume tells you what happened earlier. Depth tells you what is available now. If you can only trade a small size without moving the price, the contract is illiquid for you, even if it shows a flashy historical volume number.

3) Concentration: are you trading a crowd or one wallet?

In thin markets, a single participant can dominate. When that happens, the price can look “confident” while being fragile. You want diversity of independent participants, not one whale shaping the curve.

This matters even more around resolution. If you have not read it yet, start with our resolution explainer: How Oddup markets resolve.

4) Time-to-event: liquidity often compresses

Many contracts are quiet until the final window. Then liquidity jumps, spreads tighten, and information arrives faster. That sounds good, but it also increases adverse selection risk. You are more likely to be trading against someone who knows something now.

Trade plan: decide your “information threshold”. If you are trading because of a thesis, enter when the thesis is still underappreciated. If you are trading because you saw a headline, you are probably late.

5) Resolution clarity: the underpriced variable

A market with messy resolution rules behaves like a market with hidden volatility. If your payout depends on a disputed definition, you are not trading probability. You are trading governance.

This is where a third outcome can help. If the honest truth is “we may not get a clean yes/no”, Maybe can be a more accurate expression of uncertainty.

Worked example: trading uncertainty, not just direction

Pick a real contract type you will see often: a short-dated macro question, a sports outcome, or a crypto price bracket. The details change, but the liquidity logic is the same.

Let’s model a scenario:

• Yes: the event happens exactly as defined.
• No: it clearly does not.
• Maybe: partial fulfilment, contested interpretation, or “close enough” uncertainty is plausible.

Your first step is not to pick Yes or No. Your first step is to audit the market:

1. Is the spread tight enough to justify entry?
2. Is there visible depth on both sides?
3. Is volume concentrated in one burst, or consistent over days?
4. Is the resolution source explicit and credible?

If any of these fail, your edge must be high to compensate. In most cases, it is not.

Now, assume liquidity is acceptable. Here is how the third outcome changes your thinking:

• If your thesis is “the market is overconfident”, Maybe is often the cleanest expression.
• If your thesis is “the timing is wrong”, Maybe can reduce the penalty for being early.
• If your thesis is “resolution ambiguity is being ignored”, Maybe is a direct bet on that ambiguity being priced in later.

Again, Maybe is not a guaranteed return. It is a different payoff curve.

Why this matters for prediction traders

Prediction markets reward being right. But they punish being sloppy about structure. In practice, many losses come from microstructure, not from “bad forecasts”:

• you paid a wide spread,
• you moved the market against yourself,
• you got picked off near the close,
• or you misunderstood resolution and traded governance risk.

If you treat volume as a proxy for safety, you will mis-size positions and misread risk. Instead, treat every contract as its own market. Audit depth, clarity, and participation. Then decide which outcome expresses your edge with the least hidden cost.

Compliance disclaimer: This article is for general information only and does not constitute financial advice, investment advice, or a recommendation to trade. Prediction markets involve risk and you can lose money. Always read the market rules and resolution sources before trading.