When we look at the stock price S of a stock, then if I am correct S is equal to the average between the highest bid and the lowest ask for this stock. Hence since the highest bid is lower than the lowest ask: we have : S < lowest ask

So when I execute a market order, I buy a share of the stock at the price S. But then who can sell me this share since S < lowest ask no one can sell me a share at a price of S ?

So what I don't get is that there is no actually no offer for a price of S so when I execute a market order what price do I pay for the share ? The lower ask and not the stock price ?

1 Answer 1


when I execute a market order, I buy a share of the stock at the price S

No, when you place a market buy order, you buy stock at the current (lowest) asking price. The "published" price S can be the last traded price, or the current bid, ask, or midpoint, depending on who is publishing it. Market data aggregators like Google tend to just publish the last price, but brokers may publish the ask (or both the bid and the ask) to show you what you can buy the stock for, and analysts may use the midpoint.

  • Ok I see thank you. But for example when I type: apple stock price in google, which price is printed ? The midpoint or the last traded price ? Feb 20, 2023 at 23:54
  • 3
    Most likely it's the last trade - for highly liquid stocks the bid/ask range is very small ,so there should not be much difference between the last price, the midpoint, and the ask.
    – D Stanley
    Feb 21, 2023 at 1:55

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