# How do limit order prices meet?

I understand how limit orders work but I don't know how do they meet. Suppose the book of a ticker ABC is empty. Trader 1 sends a buy limit order for 1 share of ABC at 2\$, and at the same time (ideally speaking, simultaneously) Trader 2 sends a sell limit order for 1 share of ABC at 1$. What will be the transaction price?

In this question, the "accepted" answer says that it depends on the arrival position, it is a "race condition", so the last order to arrive will execute against the first.

If we suppose that Trader 1 was the first one to send the order by a microsecond, what does it mean this solution? What does it mean that Trader 2 will be executed against the price of Trader 1?

Does it mean that Trader 2 will sell at 2\$? So, here Trader 1 won't take full advantage trying to buy for less than 2$?

Thanks,

• The anwer to this is both exchange specific, also dependent on the trading style of the instrument you're looking at, and then again it can be dependend on the currernt trading segment, and a bunch of other scenarios (i.e. are we currently in a volatility auction? Is there a market pause due to a circuit breaker? Is the price up against a limit (i.e. maximum price move)? etc.). The rules you're looking for are often called matching rules, and information can be found on the exchange website where the instruments you're interested in trade. – will Jan 9 at 13:57
• Thanks! It is true that I did not specify the conditions of the operation. I tried to consider the simplest and most hypothetical scenario. I will research about what you mentioned, "matching rules". – Ignasi Piqué Muntané Jan 9 at 15:01