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Documentation Index

Fetch the complete documentation index at: https://docs-polymarket-us.mintlify.app/llms.txt

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Polymarket US does not support fractional contracts. All trades are executed in whole event contracts.

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How It Works

When you buy using a dollar amount, the system purchases as many whole contracts as that amount can buy at the current market price. Any remaining amount that is not enough to buy a full contract returns to your cash balance.

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Example

You want to spend 100 dollars to buy Yes contracts priced at $0.65:
  • Each contract costs $0.65
  • 100 ÷ 0.65 = 153.84 contracts
  • You receive 153 whole contracts for $99.45
  • The remaining $0.55 returns instantly to your cash balance
Only whole contracts are purchased. No fractional amounts are created.

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Key Points

  • Polymarket US only supports whole contracts
  • When buying with a dollar amount, you receive the maximum number of whole contracts available at the current price
  • Any unused amount that cannot buy a full contract returns immediately to your cash balance