Position Merge Event

Emitted when outcome tokens (YES + NO shares) are merged back into collateral (USDC) via the Conditional Tokens Framework mergePositions function. The inverse of a position split. Merges are much rarer than splits (~20x less frequent). They happen when a trader holds both YES and NO tokens for a condition and redeems them back to USDC.

{
  "data": {
    "amount": 1414.0,
    "block_number": 84090704,
    "collateral_token": "0x3a3bd7bb9528e159577f7c2e685cc81a765002e2",
    "condition_id": "0xd1747284d6048b2a3dcfbee489db405f36de18f9590197dd0e5c9f0c246bf050",
    "event_title": "Republican Presidential Nominee 2028",
    "event_type": "position_merge",
    "log_index": 1004,
    "market_image": "https://polymarket-upload.s3.us-east-2.amazonaws.com/Byron_Donalds.png",
    "market_slug": "will-byron-donalds-win-the-2028-republican-presidential-nomination",
    "market_title": "Will Byron Donalds win the 2028 Republican presidential nomination?",
    "neg_risk": true,
    "stakeholder": "0xd91e80cf2e7be2e162c6513ced06f1dd0da35296",
    "taker_base_fee": 0.0,
    "tick_size": 0.001,
    "timestamp": 1773301441000,
    "tokens": {
      "311624663652221737215322113380496984764966764039692273354641152455298576851": "Yes",
      "43292374563904271719486871569114922516560719431752184778538513591321835161630": "No"
    },
    "tx_hash": "0x92fa6de980f6cad9eae9ef28e908d19faa10838a07f01352b0cae63b5f8299fb"
  },
  "timestamp": 1773301441000,
  "type": "position_merge"
}

Fields

string

required

Always "position_merge".

number

required

Block timestamp in Unix milliseconds.

object

required

Show data fields

string

required

Transaction hash.

number

required

Block number.

number

required

Log index within the transaction.

number

required

Block timestamp in Unix milliseconds.

string

required

Address that triggered the merge.

string

required

Collateral token address. USDC.e (0x2791bca1f2de4661ed88a30c99a7a9449aa84174) for standard markets, wrapped collateral (0x3a3bd7bb...) for neg_risk markets.

string

required

Market condition ID — identifies which market’s outcome tokens were burned.

number

required

USDC amount received from merging outcome tokens (6 decimal precision).

string

Human-readable market question. Populated when metadata is available.

string

URL slug for the market.

string

Market image URL. Enriched from metadata.

string

Parent event title. Enriched from metadata.

boolean

Whether this market uses the negRisk contract type. Enriched from metadata.

number

Minimum price increment (e.g. 0.01 or 0.001). Enriched from metadata.

number

Taker fee rate in basis points. 200 = 2%, 1000 = 10%, null = no fee. Short-term crypto markets (5-minute ETH/BTC) typically have 1000 (10%), while standard markets have 200 (2%). Enriched from Polymarket metadata.

object

Map of token ID → outcome name for all outcomes in this market. Enriched from metadata.

Use cases

Position unwinding — detect when traders are closing positions by merging outcome tokens
Liquidity withdrawal tracking — merges reduce the total supply of outcome tokens in a market
Arbitrage detection — merges after buying both outcomes at favorable prices signal arbitrage

Not included in global firehose (full data stream) by default. Subscribe explicitly with event_types: ["position_merge"] or use the wallets/markets subscription types which include it automatically.

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Position Merge Event

Fields

Use cases

​Fields

​Use cases

Fields

Use cases