Yield-bearing token Converters

Hello Fellowship!

I’m working with yield-bearing tokens, and some implementation details are making my life harder, so I’d like to propose a standard if there’s nothing else out there that solves this issue. These tokens can accrue value through time, but this accrual can be represented as rebasing tokens or as exchange rate tokens.


  • asset: This unit measures the pool’s value. At time t, the pool has a total value of TotalAsset(t) assets.
  • shares: A unit that represents ownership of the pool. At time t, there are TotalShares(t) shares in total. One user u has sharesOf[u], and only a new transfer changes this value.
  • exchange rate: At time t, the exchange rate ExchangeRate(t) is simply how many assets each shares is worth ExchangeRate(t) = TotalAsset(t) / TotalShares(t)
  • rebasing tokens: the tokens that implements their balanceOf method as sharesOf[u] * ConvertionRate(t). That means the return value from balanceOf can change even without a transfer to/from the user u.
  • exchange rate tokens: the tokens that implement their balanceOf method as just sharesOf[u], so the return value from this method is constant if no shares are transferred to/from the user u. They use the ExchangeRate(t) method upon withdrawal/burn of the shares of a user.


  • rebasing tokens: stETH from Lido.
  • exchange rate tokens: cTokens from Compound.

Contracts that integrate with rebasing tokens tend to break with exchange rate tokens and vice-versa, and that’s where a converter from one type to another becomes handy. While this is relatively simple, I think the community would benefit from the added safety that a standardized and audited reference implementation would bring.

While I did find a reliable and safe converter from rebasing token to exchange rate token on 0x7f39C581F595B53c5cb19bD0b3f8dA6c935E2Ca0 (wstETH contract on mainnet), I couldn’t find the other way around (from exchange rate token to rebasing token).

Do you think that’s something worth opening an EIP for?