How order book work on nash?

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#1

Hi, from start apology for my English.

I have question about order book on nash. How it works?

Today I place sell order on 10597.0 at 19:29:03.

How I think order book works:
I place order and that order is with position 10 and I must wait to get 9 positions before me get filled or canceled.

What happens?
My order start getting filled by 42% at 19:33 ± (That’s the moment When my order is with position 1 and noone is before me).

On screens you Can see What happen next.

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at 19:42 (49%)

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at 19:47 (49% still but in recent trades you can see buy orders at that level Where is my sell order)

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At 19:58 (43% but in recent trades you can see more buys at that level)

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Thanks for answers,
Patrik

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#2

Interesting. Curious how the prioritization works

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#3

The way you expect an orderbook to work is the same I do: FIFO (First In First Out)

What happened to you matches what @Zino just experienced: it feels like order matching is now matching using LIFO (Last In First Out).

@canesin Could this be a regression introduced by some recent changes?

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#4

I think it’s more complicated than that. Sometimes, the matching engine begins to fill the order then stops and fills other orders. It’s not FIFO neither LIFO :laughing:

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#5

Or perhaps bots are able to place orders with more decimals?

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#6

Matching is strict FIFO, there is no priority besides price and time.

On my speculation looking at it what can be happening is a visualization artifact where orders placed on the inverse market USDC/BTC on this case have a different precision level and are in truth slightly better priced - that should not happen if orders are being placed from the UI.

That confusion was one of the main reasons we removed the UI for inverted markets, but they are still available through the API because they are needed for market buys - a legacy issue that we intend to resolve by replacing current market orders with limit orders with defined slippage.

But as on the post shared with @Zino we will look at the specific trades and see what happened there.

The matching engine has hundreds of automated tests that run on every commit before allowing any changes being added to it - those tests include order matching priority.

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