Market Trading Cycle
The BOX daily trading session is divided into three distinct phases which are described below.
Pre-Opening Phase
Orders may be submitted, modified, and cancelled throughout the Pre-Opening phase preceding the start of the market. In addition, any open and unexecuted orders from the previous trading session, which are still valid, are carried forward to the Pre-Opening phase and may be modified or cancelled.
Throughout this period, a Theoretical Opening Price (TOP) is calculated and broadcast to all Participants. The TOP is the price at which opening trades would occur if the opening were to be executed at that given moment (refer to the following section for details). No trade matches occur during the Pre-Opening phase.
Opening Match Price Phase
The opening match for each option class (i.e., each of the individual options instruments within the class) occurs shortly after the opening for trading of the underlying equity. The Opening Match price is the price at which the highest number of options contracts match. Should two or more prices result in the execution of the same number of contracts, BOX uses a "tie breaker" algorithm to open trading.
Continuous Trading Phase
The Options Market Model is founded upon a central, anonymous, electronic order book, utilizing a price/time algorithm for order matching. Orders are booked sequentially, if not immediately executable.
Trading Hours
The BOX market trades continuously after the opening of the underlying stock or Exchange Traded Fund (ETF) in its primary market at 09:30 EST until the close of the equity markets (16:00 EST). Certain ETF option classes may close, later, at 16:15 EST.
Trading Halts
If the suspension of trading in the underlying is due to a trading halt issued by the host exchange, trading in the related options class will be halted as well.
