# What is the final price if the bid price exceeds the ask price in an order driven market? [duplicate]

Let's assume a very simplified situation. There is only one seller asking for 10\$ and there is only one buyer bidding 20\$. At what price would the transaction go?

Some answers say it won't, because the ask price has to match the bid price. (Does a market maker sell (buy) at a bid or ask price?) Other answers say, that the time ordering is important. (Bid-Ask at market open, which comes first?) Which answer is correct? What is the final price in the presented situation?

The earliest order is the price.

If the seller submits a Limit Order to Sell at \$10 at 9:30 AM, it will enter the order book and \$10 will be shown to the world as Best Ask.

Then if the buyer submits a Limit Order to Buy at \$20 at 9:31 AM, it becomes a Marketable Limit Order because \$20 is better than the Best Ask of \$10.

The trade will be executed at \$10, not somewhere between \$10 and \$20.

That limit order to buy at \$20 will never be shown in the order book, nor will the \$20 be shown as best bid.