Earlier today I decided to place a Limit Buy order for some stock for a target price somewhere in the middle of the Ask-Bid spread. Since the price of my order was higher than the Bid, I would have expected my price to become the new Bid price, which however was not the case.

Moreover, in the hours that followed the stock's price went down, which means that trades were made at a price lower than my Limit Buy. How come my order did not execute?

  • 1
    Did you place the order for 100 or more shares? Or did you place something like 5 shares? Did you apply any attribute such as All Or None? – base64 Mar 19 at 16:28
  • It was way more than 100 shares, and I did not apply any such attribute explicitly but I used Trade Republic and perhaps they do it implicitly? I will check again. – Guybrush Threepwood Mar 19 at 18:31
  • According to their website they support partial execution so there shouldn't be any such thing applied automatically. – Guybrush Threepwood Mar 19 at 18:48

On US stock exchanges, odd lots do not affect the price or the volume size of the NBBO quote. So if you order was for less than 100 shares, you'd see no change in the quote.

If you buy limit order was equal to or greater than the ask price then you should have gotten a fill. However, if it was less than the ask, you could see trades occurring at a lower price without a fill.

For example, XYZ is $50.00 x $50.30 and you place an order to buy at $50.05. XYZ could slowly drop to $49.80 x $50.10 and you could see lots of trades from $50.30 to $49.80. However, the ask price never reached your order's limit price so there was no trade execution.

  • How would XYZ trade at $49.80 without filling the buy order at $50.05? – nanoman Mar 19 at 17:53
  • @nanoman - If the NBBO quote is $49.80 x $50.10, a seller at the market would print at $49.80. If the OP has placed an odd lot limit buy order for $50.05, it's not reflected in the quote and his price of $50.05 is below the current ask price. Hence, no fill. – Bob Baerker Mar 19 at 18:40
  • That's interesting. How do I know if my order size is significant in that way or not? Is it a hard global limit of 100 pieces, or does it depend on other orders placed? – Guybrush Threepwood Mar 19 at 18:53
  • My explanation is applicable to US markets. I don't know how it's handled elsewhere. – Bob Baerker Mar 19 at 19:00
  • Does that mean that someone selling at $49.80 would fill the order at $50.05 if they're on the same exchange, but not if they're on different exchanges? – nanoman Mar 19 at 19:07

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