# Polymarket Volume and Open Interest Tracker

> Polymarket volume by day, counted once per trade, with open interest, active traders and volume by category, read from Polymarket's contracts on Polygon.

Markdown copy of https://voltfincrypto.com/apps/polymarket-volume-open-interest

**Question:** How much is traded on Polymarket each day, and how much collateral is locked in open positions?

- Kind: Dashboard in Voltfin Vantage
- Topic: [Markets and trading](https://voltfincrypto.com/topics/trading)
- Chains: Polygon
- Status: Planned. The data is not published yet, so this page states no figure; each figure will open its receipt when it is.

Polymarket is a prediction market: traders buy and sell shares in the outcomes of real-world questions, and each share pays out one unit of collateral if its outcome happens. Every trade settles on Polygon, so the volume, the collateral behind open positions and the number of traders can all be read from Polymarket's own contracts rather than taken from its website.

This dashboard counts each trade once, from the taker's side, because every match emits a fill event for each side of the trade and adding them all counts the same trade twice. Open interest is the collateral held against positions that have not yet been merged or redeemed. Every figure is pinned to the block it was read at, with the transactions behind it.

Use it to see how busy the market is day to day, which categories draw the most trading and how much money stays committed between a market's opening and its resolution. Polymarket has upgraded its contracts over time, so each series joins every contract version and marks the day of each switch.

## Blueprint

### Overview

Volume, open interest and traders on the latest complete day, with their history.

- **Volume, last day** (USD): Collateral value of trades matched on the latest complete UTC day, counted once per match from the taker's fill.
- **Volume, last 7 days** (USD): Matched volume summed over the last 7 complete UTC days, on the same once-per-trade count.
- **Open interest** (USD): Collateral locked behind outcome shares not yet merged or redeemed, at the latest day's last block.
- **Active traders** (count): Distinct wallets that traded as maker or taker on the latest complete day.
- **Volume by day** (USD): Daily matched volume over the selected period, counted once per trade, with the day of each contract upgrade marked.
- **Open interest by day** (USD): Collateral locked behind open positions at each day's last block over the selected period.

### Markets

Which categories and markets draw the trading.

- **Markets traded** (count): Markets with at least one matched trade on the latest complete day.
- **Largest category's share** (%): Share of the period's volume traded in its largest market category, such as sports, politics or crypto.
- **Volume by category** (USD): Daily volume split by market category, using the categories in Polymarket's public metadata.
- **Largest markets**: Markets ranked by volume over the selected period, with open interest, traders, category and end date.

Filters: Period (Last 7, 30 or 90 days, or since launch); Category (Every market category in Polymarket's metadata).

## How it will be measured

- Volume is the collateral value of matched trades from OrderFilled events of Polymarket's exchange contracts on Polygon, counted once per match from the taker's fill; mints, merges and redemptions are not trades and are left out.
- Open interest is the collateral locked behind unredeemed positions: the collateral token balance of Polymarket's position and adapter contracts at each day's last block.
- Active traders are the distinct wallets that appear as maker or taker in a day's fills. One person can control several wallets, so this counts wallets, not people.
- Market questions and categories come from Polymarket's public market metadata, an off-chain label joined to each market's on-chain identifier and recorded with its source.
- Every figure carries a receipt with its block, the time of the read and the contract read or events summed behind it.

## Data it needs

- `prediction_markets_daily` (to build): Volume, open interest and traders per prediction market and category per day.
- Source: OrderFilled events of Polymarket's CTF Exchange and NegRisk CTF Exchange on Polygon, and of the exchange contracts that replaced them
- Source: PositionSplit, PositionsMerge and PayoutRedemption events of the ConditionalTokens contract, and their successors in the newer positions contract
- Source: Collateral token balances (USDC.e and Polymarket USD) of the position and adapter contracts at day-end blocks
- Source: Distinct maker and taker wallet addresses in each day's fills
- Source: Market question, category and end date from Polymarket's public market metadata (off-chain labels)

## Questions

### How is Polymarket volume calculated?

Volume adds up the collateral that changed hands in matched trades. Each match emits a fill event for the taker and one for every maker it filled against, so this dashboard counts the taker's side only, which gives each trade once.

### What is open interest on Polymarket?

Open interest is the collateral locked behind outcome shares that are still outstanding. When a trader mints a full set of outcome shares, collateral goes into the contract; it leaves when sets are merged back or winning shares are redeemed.

### Which blockchain does Polymarket use?

Polymarket settles trades on Polygon PoS. Orders are matched off-chain by its operator and then settled on-chain by its exchange contracts, so every executed trade, mint and redemption is a Polygon transaction anyone can check.

### Why do Polymarket volume figures differ between sources?

Sources differ in what they count: some add both sides of every match; some count shares rather than collateral; some include mints and merges. This dashboard states its definition beside each figure, so it can be compared with any other.

### Are Polymarket traders anonymous?

Trades come from wallet addresses, usually proxy wallets that Polymarket deploys for each account. The dashboard counts wallets and never tries to identify the people behind them.

## Glossary

- **Outcome share**: A token that pays one unit of collateral if its outcome happens and nothing if it does not. Its price reads as the market's implied probability.
- **Open interest**: The collateral locked behind outcome shares that have not yet been merged or redeemed.
- **Taker**: The side of a trade that crosses the spread and fills against resting orders, which belong to the makers.

## Related apps

- [Prediction Market Volume by Platform](https://voltfincrypto.com/apps/prediction-market-volume)
- [Perp DEX Volume and Market Share by Venue](https://voltfincrypto.com/apps/perp-dex-volume-market-share)
- [Polygon Stablecoin Payments: Volume, Senders and Sizes](https://voltfincrypto.com/apps/polygon-stablecoin-payments)
- [Polymarket Top Traders: Volume and Realized Profit](https://voltfincrypto.com/apps/polymarket-top-traders)
- [Prediction Markets Monthly Report: Volume and Share](https://voltfincrypto.com/apps/prediction-markets-monthly-report)
- [Stablecoin Exchange Inflows and Outflows: USDT and USDC](https://voltfincrypto.com/apps/stablecoin-exchange-inflows-outflows)

Build it in Voltfin Studio: https://app.voltfincrypto.com/signup?next=%2F