ID 0xbb14faf85f1b0bff9b31af11d11b045dd19c244046028ba2d62ece10f974425c basically I had entered an eth-USDC swap through matcha. I even had the USDC in my wallet for like 5 seconds but then I ended up with all WETH, and a loss from 300 eth to 292 WETH.

My own conclusion is that the transaction tried to go through but maybe because of pricing issues 0x had to revert and tried to give me back my initial balance in WETH but was unable to complete at 100%.

I asked matcha help and was told that I had entered an eth-weth transaction and this is normal. But an eth-weth would not run like this, nor slip 300 to 292.

  • im still looking on my own. you can see on the next eth block is when i started getting WETH into my wallet from avve but it wasnt my own transaction. next block transaction hash 0xbfe844c04c1c330cb0a29295c0cbf4f4bcfad05bd327386c641cf8b15fb4557f
    – Altyeom
    Commented Jan 23, 2022 at 18:39
  • Quite difficult to say. Assuming there are no bugs in the contracts, it shouldn't be possible that assets are lost because something "fails". Slippage may cause loss of funds, but "failures" shouldn't. Also it sounds quite dangerous if some service returns funds in the next block. But not familiar with Matcha or Aave. Commented Jan 23, 2022 at 18:46

1 Answer 1


This is quite puzzling. Here is what I have been able to find so far.

First, you swapped Eth for USDC with this tx. It completed successfully and you received the USDC.

Then, just 1 block after this transaction, another address called an unverified contract with this tx. This unverified contract took 630K$ USDC from your address and exchanged it for 584K$ WETH.

As you pointed out in comments, other transactions did the same in the following transactions.

It seems that you placed a limit order to exchange USDC to WETH with a "bad" price. Some bot traders took advantage of this to close the order at your bad price and made a profit doing so. Matcha documentation says than a limit order can be partially filled and so this is why it was filled in multiple transactions over a few blocks.

  • it actually keeps going for the next 2 blocks after that. the Eth-USDC was a single market order. heres the next 2 blocks 0x74b45e8082daaa3ccbaac215aff947d6006a6f4f97f7343a4fc8df0695970467 0x26e17de9e3cae369c6263c88676a6b0bef58055be2687231c3f724b286ee97e3
    – Altyeom
    Commented Jan 23, 2022 at 19:36
  • See my edit. I added some details with what I think happened.
    – Undead8
    Commented Jan 23, 2022 at 19:49
  • FYI, if you are satisfied with the answer, you have to click the check mark to accept it.
    – Undead8
    Commented Jan 23, 2022 at 19:49
  • hmm so i just got sandwiched? doenst show on sandwitched.wtf though
    – Altyeom
    Commented Jan 23, 2022 at 19:51
  • You were not sandwiched. You posted a limit order saying "I want to trade X for Y at 10$" The market price was 9$, so traders bot purchased the asset at 9$ and sold it to you at 10$.
    – Undead8
    Commented Jan 23, 2022 at 19:53

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