# Tracing + token flow analysis

### Primer

### Process

Aside from the EOA initiating the transaction itself, we check for balance changes for the `contract` (in the `to` field of the tx) that executes the arb/liquidation but also `proxy` contracts that can be identified by looking at the delegate calls (if any) in the tx traces.

Types of traces (by `action_type`):

* `Call`, which happens when a method on the same contract or a different one is executed. We can identify the input parameters in each instance by looking at this trace.
* `Self-destruct`, when a arbitrage contract destroys the code at its address and transfers the ETH held in the contract to an EOA. Common pattern among searchers given gas refunds.
* `Create`, when a contract deploys another contract and transfers assets to it.
* `Reward`, pertaining to the block reward and uncle reward, not relevant here.


More on delegate calls: https://medium.com/coinmonks/delegatecall-calling-another-contract-function-in-solidity-b579f804178c

### Examples

**Simple Arb across DEXs**

Example:

https://etherscan.io/tx/0x4121ce805d33e952b2e6103a5024f70c118432fd0370128d6d7845f9b2987922

ETH=>ENG=>ETH across DEXs

Script output:
EOA: 0x00000098163d8908dfbd126c873c9c4732a2c2e6
Contract: 0x000000000000006f6502b7f2bbac8c30a3f67e9a
Tx proxy: 0x0000000000000000000000000000000000000000
Stablecoins inflow/outflow: [0, 0]
Net ETH profit, Wei 22357881284770142

^accurate and accounts for gas spent

**Arb flowing through stablecoin**

Example:


https://etherscan.io/tx/0x496836e0bd1520388e36c79d587a31d4b3306e4f25352164178ca0667c7f9c29

Here the `contract` flows through the tether pool but only for the arb and they exit without any at the end.

Script output:

EOA: 0xcbb9feb9f882bb78b06ca335ee32f13a621c1a35
Contract: 0x000000000a2daefe11b26dcdaecde7d33ad03e9d
Tx proxy: 0x0000000000000000000000000000000000000000
Stablecoins inflow/outflow: [871, 871]
Net ETH profit, Wei 2848191823313317

**Arbs through multiple stablecoins**

Example: 

https://etherscan.io/tx/0x5ab21bfba50ad3993528c2828c63e311aafe93b40ee934790e545e150cb6ca73

Script output:

EOA: 0x46eaadc8f2199463db26d1797131900575f0d264
Contract: 0x5a48ae20173382884929dd5e130ed9b81931ea88
Tx proxy: 0x0000000000000000000000000000000000000000
Stablecoins inflow/outflow: [0, 0]
Net ETH profit, Wei 46223431362651237

Here we notice the stablecoin inflow/outflow to be 0 despite flowing through them, this is because for those trades, the coins are transferred between the router and not the eao/contract/proxy, so they do not have to be accounted. We still get the net MEV profit accurately without having to look at the different tokens involved.