Trader Whale Trade

Event: trader_whale_trade
Endpoint: wss://api.struct.to/ws/alerts
Cost: 0.2 credits per event

Fires when a trade exceeds the configured USD size threshold. This is the primary event for tracking large trades across Polymarket, commonly used to follow whale activity and detect significant market-moving positions.

Filters

Filter	Type	Required	Description
`wallet_addresses`	`string[]`	No	Restrict to specific trader wallet addresses (max 500)
`min_usd_value`	`number`	Yes	Minimum trade size in USD
`condition_ids`	`string[]`	No	Restrict to specific markets (max 500)
`event_slugs`	`string[]`	No	Restrict to specific events (max 500)
`min_price`	`number`	No	Minimum probability threshold (0.0 to 1.0)
`max_price`	`number`	No	Maximum probability threshold (0.0 to 1.0)
`exclude_shortterm_markets`	`boolean`	No	Exclude short-term “updown” markets

{
  "op": "subscribe",
  "event": "trader_whale_trade",
  "min_usd_value": 10000,
  "exclude_shortterm_markets": true
}

Response

{
  "event": "trader_whale_trade",
  "timestamp": 1775913505260,
  "data": {
    "trader": "0x1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b",
    "taker": "0x1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b",
    "position_id": "13579",
    "condition_id": "0x4fec624c0ff2bfae89956cebd6fbc9c58f995f824382dc587dc5a32a4b15940b",
    "outcome": "Yes",
    "outcome_index": 0,
    "question": "Will ETH reach $10k by December 2026?",
    "market_slug": "will-eth-reach-10k-by-december-2026",
    "event_slug": "eth-price-milestones",
    "image_url": "https://polymarket-upload.s3.us-east-2.amazonaws.com/will-eth-reach-10k-by-december-2026.png",
    "trade_id": "jkl012",
    "hash": "0xfedcba0987654321fedcba0987654321fedcba0987654321fedcba0987654321",
    "block": 58321500,
    "confirmed_at": 1713021600,
    "amount_usd": 50000,
    "shares_amount": 71428.57,
    "fee": 100.00,
    "side": "Buy",
    "price": 0.70,
    "probability": 0.70,
    "exchange": "Polymarket",
    "trade_type": "OrderFilled"
  }
}

price and probability are not the same field:

price: the outcome you are looking at (the token in outcome_index / position_id).
probability: always outcome index 0 (the Yes/Up token), no matter which outcome the payload is about.

They are equal only when outcome_index is 0. On the No side (index 1) they are complements: a price of 0.40 pairs with a probability of 0.60.

Last modified on June 17, 2026

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