# Polymarket US Open interest Methodology

## 1. Overview

Open interest is defined as the total USD notional value of all open positions on a derivatives protocol at a point in time. For Polymarket US, open interest is calculated using the face value of open contracts, where each contract is valued at a constant rate of $1. This metric is utilized as a leading indicator of speculative activity and capital at risk. Positions that have already been closed or liquidated within the period are excluded from the final calculation.

## 2. Data sources

- **Off-chain reports**: Daily market reports scraped from the Polymarket US exchange, covering off-chain activity

## 3. Step-by-step calculation

### Component A: Daily market report extraction

- **Purpose**: Extract raw open interest data from the latest available daily market reports
- **Logic**: Raw daily market reports are ingested from the Polymarket US exchange scraper. The latest files are identified by matching the file date and insertion timestamp against the daily market report registry. For each active market symbol, the business date and open interest values are extracted.
- **Key fields**: `business_date` (timing), `symbol` (market identifier), `open_interest` (position value)

### Component B: Open interest aggregation

- **Purpose**: Aggregate open interest to a daily protocol-level metric
- **Logic**: The extracted open interest values are grouped by business date. The business date is converted to a standard daily timestamp, and the open interest values across all market symbols are summed to produce a single daily total for Polymarket US. The chain identifier is designated as off-chain.
- **Key fields**: `business_date` (converted to timestamp), `open_interest` (summed value)

### Component C: Forward-filling and capping

- **Purpose**: Ensure continuous daily data while preventing out-of-bounds propagation
- **Logic**: Gaps between reporting days are resolved by forward-filling the last known open interest value. To prevent the metric from projecting values into the future beyond the exchange's actual reporting history, the time series is capped at the maximum timestamp present in the source market reports.

*This methodology was automatically generated by Token Terminal's methodology analyzer.*

Total USD notional value of all open positions on a derivatives protocol at a point in time.

Open interest

Prediction markets

Liquidity providers deposit funds into Polymarket and receive trading fees from traders (supply-side fees). Polymarket has also launched a new peer-to-peer order book with no liquidity providers involved.

Polymarket is a non-custodial prediction market protocol built on Polygon. Polymarket was founded by Shayne Coplan and launched in 2020.

Polymarket team & investors own and govern the protocol. They do not currently take a cut of the total trading fees paid by traders (revenue). Polymarket's investors include Polychain, 1Confirmation, ParaFi Capital, etc.

Polymarket US

Open interest

Open interest

Chain breakdown