Stock Price Formulation

What are simultaneous orders, and how are they distributed?

Update : Jan. 04, 2010

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Answer:

As explained in 'How is order priority decided?', orders are normally executed on the basis of price and time priority.
However, in the following circumstances orders are treated as simultaneous orders and time priority is ignored:

  1. All orders placed before the opening price is determined
  2. All orders placed before the determination of the initial price after resumption of trading after a temporary trading halt
  3. All orders at the daily limit price, which will be executed with market orders at the closing price of the afternoon session

Note: All remaining orders from the morning session are treated as simultaneous orders at the beginning of the afternoon session.(Please 'What is a closing auction at the limit price?' for more details.)

These simultaneous orders are executed according to a mechanism determined by TSE as set out below.

<Distribution of simultaneous orders>

  • TSE totals up the orders from each Trading Participant and arranges them in descending order from the Trading Participant with the largest order. 1 unit shares each in turn are then distributed.

Thus simultaneous orders are executed in proportion to the total amount of each Trading Participant's orders. Trading Participants then distribute the shares among their customers according to their own internal guidelines.

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