Skip to main contentAsset Master Structure
Every instrument on the Polymarket Exchange follows a hierarchical structure that organizes markets by category, series, event, and product type.
Category
Categories provide the broadest classification level, organizing instruments by the type of events they represent. Each instrument belongs to exactly one category. This is surfaced in instrument metadata:
event_category - Category code (e.g., spr, cul, fin, mac, pol, cry, cli, men)
Examples: Sports (SPR), Culture (CUL), Finance (FIN), Macro (MAC), Politics (POL), Crypto (CRY), Climate (CLI), Mentions (MEN)
Series
A more specific classification within each category, such as sports leagues, specific topics, or individual assets. This is surfaced in instrument metadata:
event_series - Series code (e.g., cbb, nfl, nba, usp, btc)
Examples: National Hockey League (NHL), National Basketball Association (NBA), National Football League (NFL), College Basketball (CBB), College Football (CFB), Golden Globes (GGB), US Presidential (USP), US Midterms (USM), Bitcoin (BTC), Ethereum (ETH)
Product
The type of contract structure used to format instruments associated with an event. Each product is documented in full on polymarketexchange.com. This is surfaced in instrument metadata:
instrument_product - Product code (e.g., aec, asc, tsc, tec, tac, ewc)
instrument_product_series - Combined product and series (e.g., aec-cbb, ewc-usp)
Examples: Athletic Event Contract (AEC), Athletic Spread Contract (ASC), Total Score Contract (TSC), Title Event Contract (TEC), Title Award Contract (TAC), Election Winner Contract (EWC)
Event
Events represent specific occurrences with multiple possible outcomes. Each event consists of one or more instruments representing the complete set of outcomes traders can speculate on. This is surfaced in instrument metadata:
event_id - Unique event identifier (e.g., nfl-hou-mia-2025-12-16)
event_rules - Resolution rules and criteria for the event
event_start_time - Event start timestamp (UTC)
event_tags - Comma-separated tags for categorization
event_external_id.sportdataio - External data provider ID (SportsDataIO)
event_external_id.sportdataradar - External data provider ID (Sportradar)
Examples: nfl-hou-mia-2025-12-16, usp-pres-2028-11-07, btc-15min-updown-1765593600
Instrument / Market
The tradable symbol, which follows consistent naming conventions and metadata practices to allow for easy identification and sorting. This is surfaced in instrument metadata:
instrument_rules - Resolution rules specific to this instrument (often matches event_rules for simple instruments)
Examples: aec-nfl-buf-nyj-2025-01-15, asc-nfl-hou-mia-2025-12-16-4-5, tac-ggb-bmpd-2026-01-11-sinners
Participants
Each instrument has participants representing the possible outcomes. The long participant represents the “Yes” outcome that traders buy and sell. This is surfaced in instrument metadata:
participant_type - Type of participant (team, player, nominee, candidate, etc.)
long_participant_id - Globally unique ID for the long side (e.g., cbb-akron, nfl-buf)
long_participant_name - Full display name for the long side (e.g., “Akron”, “Buffalo Bills”)
short_participant_id - Globally unique ID for the opposing outcome (e.g., cbb-murst, nfl-nyj)
short_participant_name - Full display name for the opposing outcome (e.g., “Murray State”, “New York Jets”)
Instruments are traded by buying and selling the long participant (the “Yes” outcome). For example, in an NFL moneyline contract like nfl-hou-mia-2025-12-16, traders buy and sell HOU. Buying HOU means taking a long position on Houston winning, while selling HOU creates a synthetic long position on Miami.
There is no direct way to trade the short participant - all positions on the opposing outcome are achieved synthetically by selling the long participant.
When you sell (short) an instrument, the cash flows differ from buying. Selling 10 contracts at $0.60 means you receive $6 from the buyer, but a margin requirement equal to the maximum payout ($10 in this case) is imposed on your account. Therefore, you need $4 in available funds to enter this short position ($10 margin requirement minus $6 received). This margin requirement ensures you can cover the full payout if the outcome occurs.
Outcome
Outcome fields define the specific type and parameters of what the instrument represents. This is surfaced in instrument metadata:
outcome_type - Type of outcome (e.g., moneyline, spread, total, winner)
outcome_strike - Strike value for spread or total outcomes (e.g., 4.5 for a 4.5-point spread, 0.0 for moneyline) 
