What Is ERC-4626? The Standard Behind Crypto Yield Vaults

ERC-4626 is a shared rulebook for yield vaults on Ethereum. A vault is a smart contract you deposit tokens into so it can put them to work somewhere - lending them out on Aave, for example - and ERC-4626 says exactly which functions every vault must offer: put money in, take money out, and ask what your slice is worth right now. Nothing more exciting than that, and that is the point.

Why did vaults need a standard?

Before 2022 every vault invented its own wording. One called the deposit function deposit, another called it mint, a third wanted the amount in a different unit. A wallet or a dashboard that wanted to show your position had to be taught each vault separately, by hand. ERC-4626 settled the vocabulary, so a new vault works in existing tools on day one. It is built on top of ERC-20, the token standard almost everything on Ethereum already speaks.

What actually happens when you deposit?

Think of the vault as a shared pot and your shares as a numbered cloakroom ticket for a slice of it. You put in 100 USDC and get back vault shares - which are themselves ordinary ERC-20 tokens, so they sit in MetaMask like anything else. As the pot earns, your number of shares does not change; what one share can be redeemed for does. That is the whole trick, and it is why the standard insists every vault can answer the question "how much is one share worth today?" in the same way.

Where you will meet it

Yearn's v3 vaults, Morpho's curated lending vaults and the wrapped versions of Aave deposit tokens all follow ERC-4626. If an app shows you a token whose balance stays flat while its value creeps up, you are probably holding vault shares.

One warning worth keeping: the standard describes the plumbing, not the risk. Two ERC-4626 vaults can look identical in your wallet while one lends to blue-chip markets and the other chases something far wilder, so read what the vault actually does with the money before depositing. The token standard underneath it all is covered in our introduction to ERC-20, and the wrapping trick that lets plain ETH join in is in what wrapped ether is.