In Europe, for both the OCXL and OCXE MTF venues, OneChronos applies venue-level circuit breakers and volatility controls designed to support orderly trading in instruments admitted to trading on the venue.

The EBBO calculated for the MTF venues is derived from the primary market and Cboe. On any trading day, external venue halts contributing to the OneChronos EBBO are monitored and respected as inputs to the instrument state. If the primary market is halted, or if market data is unavailable or EBBO is crossed in any instrument admitted to trading, Onechronos will independently halt trading in the instrument. In situations where the OneChronos EBBO is incomplete, OneChronos’ own internal controls continue to prevent disorderly orders from entering the order book and preventing disorderly executions from occurring.

To ensure that reliance is not placed on the primary market and/or Cboe price volatility controls, OneChronos independently sets the following price collars:

  • Dynamic price collar and execution collar

    OneChronos applies dynamic price monitoring controls by referencing the current EBBO. Orders that breach applicable order-entry price controls may be rejected in accordance with the Rulebook and technical specifications. In addition, a potential auction execution price must be within the current EBBO ±1 tick for the instrument. If the potential auction execution price would fall outside the EBBO ±1 tick range, the auction will not execute at that price.

  • Static price collar

    At the start of each trading day, OneChronos initially applies a static price collar by referencing the previous day’s reference price on the relevant market. A potential auction execution price must be within ±40% of the static price collar and the dynamic price collar. If a potential auction execution price falls outside of both collars, OneChronos will not conclude an auction.OneChronos will halt or suspend trading in the affected instrument and review the static price collar and establish a new static price collar if the price move is legitimate, or otherwise retain the suspension if the collar was breached due to a disorderly market.

Together, these controls ensure OneChronos independently prevents and, where necessary, promptly interrupts disorderly trading, maintaining compliance with MiFID II requirements without reliance on the circuit breakers of other markets.

The triggering of a circuit breaker will result in a halt in the affected instrument rather than a shift to a different trading modality. During a halt, orders in the instrument will not execute and may be cancelled or rejected in accordance with the Rulebook and technical specifications.

The minimum duration of a halt is one auction cycle. OneChronos may maintain the halt for longer where it considers this necessary to support orderly trading, market integrity, regulatory requirements, or operational resilience.

OneChronos may also halt or suspend trading in an instrument in other circumstances, including where required due to market data, reference data, primary market status, regulatory, operational, or market integrity reasons.

The parameters underpinning OneChronos’ circuit breakers and volatility controls may be adapted from time to time depending on market conditions, instrument characteristics, regulatory requirements, or operational considerations.