Here are a list of successful trades from a Level 2 order book. The column to the left of the time the trade went through is the "trade type". It is usually one of three things:

  1. AT
  2. O
  3. Blank

Is anyone able to give a description of each? As I understand it, AT stands for Automatic and O stands for Ordinary, but I've not been able to find a description of what consitutes an "automatic" or "ordinary" trade? And if O is Ordinary, then what does no identifier represent?

Level 2 trades

  • 1
    Are you using ADVFN? If so, you should probably contact their customer support, since they did not document a blank trade type in uk.advfn.com/Help/trade-types-1549.html
    – Flux
    Commented Dec 23, 2021 at 7:07
  • Is this the list of trades for Vodafone Group Plc (VOD) on 2021-12-22? If not, what is the name of the stock? With this information, someone with access to different source of last trade information may be able to answer your question.
    – Flux
    Commented Dec 23, 2021 at 7:27

1 Answer 1


An automatic trade (AT) is a normal on-exchange trade, created during regular trading by the matching engine from order(s) in the order book.

An ordinary (O) trade is a normal off-exchange trade, agreed between the counterparties elsewhere and then reported to the exchange.

I don't think a blank type has a standard meaning; you may need to check with your data supplier.

There are many other trade types, some specific to market segments, trading session types, publication timing, &c. For example, the next most common one is probably uncrossing trade (UT), which uncrosses the order book at the end of an auction period. (The LSE lists some more here.)

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