Market Orders

Core Concept of Market Orders

A market order means:

• You want to buy or sell immediately

• You are willing to accept the best available limit order price.

• You do not specify a price, just the amount

This is ideal for traders who value speed over precision.

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Matching Logic

• We fetch and sort limit orders by price priority and timestamp (FIFO).

• Matching is based on the side:

  • BUY YES → Matches with lowest-price SELL YES

  • BUY NO → Matches with lowest-price SELL NO

  • SELL YES → Matches with highest-price BUY YES

  • SELL NO → Matches with highest-price BUY NO

• Partial Fills & Fallbacks

  • If your market order cannot be fully matched:

    • The matched portion is settled on-chain.

    • The unmatched portion is NOT stored — market orders are either fully matched or partially filled and discarded.

Maker-Taker Priority

Mettle Market uses maker-taker price priority for all matches — including standard and cross-side matches:

• The maker is the trader whose order was already resting in the order book.

• The taker is the trader who submits a new order that triggers the match.

• The trade executes at the maker’s price, not the taker’s.

This ensures:

• Makers receive their requested price

• Takers never pay more (or receive less) than they agreed to

• Price-time fairness across all trades

Even in cross-side matching (e.g. BUY YES vs. BUY NO), the first order is treated as the maker, and the match executes at that price for both parties.