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TOP Percentage (TOP %) – This parameter is not currently used by CME Globex.  It is a limiter to quantity being matched against a TOP order. Aggressing quantity is multiplied by this parameter, and the result (rounded down) is allocated to a TOP order. Unmatched quantity would then proceed to the next step of the algorithm.

FIFO - Exception

CME Globex is able to provide an efficiency to market participants in the event certain conditions are true. If an aggressing order matches all quantity at a price level from all sources, including all hidden quantity from working Display Quantity orders, CME Globex will use In the scenario where an aggressing order quantity is greater than or equal to the displayed quantity in an instrument at a given price level, for matching efficiency, CME Globex applies FIFO in lieu of the algorithm designated for the product . Fills are distributed algorithm. Quantity is allocated to resting orders prioritized by according to best price then earliest time (best priced, earliest timestamped order is filled first, followed by the best priced, next earliest timestamped order, etc.)and earliest timestamp.

This exception applies during the actual match in an instrument, not during predetermination.

FIFO Exception


  1. Aggressor quantity on one order in one event equals or exceeds resting quantity at a price level from all sources.
  2. Resting quantity includes unfilled hidden quantity from all Display Quantity orders.

CME Globex will disregard the current algorithm for the instrument and instead fill it via FIFO. Any quantity that remains unfilled from the aggressor will become a new bid or offer at the respective price level.



1. An aggressing order arrives for a quantity greater than or equal to that displayed at the given price level for the instrument.

2. CME Globex fills the resting orders via FIFO, including hidden quantity from display quantity orders.

    • Display Quantity orders are treated as their full remaining quantity (working displayed plus hidden). This prevents a display quantity order from being traded through without filling completely.
    • The FIFO exception can match through multiple price levels. In
  • this
    • such a case case, market conditions
  • 1 and 2 above
    • are
  • repeated
    • checked for each price level until
  • aggressing
    • :
      • Aggressing quantity is less than resting quantity at a price level (in which case the
  • proper
      • designated algorithm is used), or
  • until the
      • The last price level on the aggressing order is reached.
    • The GTC
  • orders have no bearing
    • order qualifier has no impact on use of
  • the
    • the  FIFO Exception.
  • Display Quantity orders are treated as their full remaining quantity (working displayed plus hidden) if the FIFO Exception is used.
  • In such a case, FIFO is used for every resting order at the affected price level until allocation complete

3. Any unfilled aggressor quantity remains on the book at the given price level.