The popular yield farming decentralized finance (DeFi) protocol Yearn Finance is progressing with its forthcoming Wrapped Bitcoin (WBTC) Vault.

The team has submitted a MakerDAO Improvement Proposal requesting whitelisting for the WBTC Vault to access upcoming oracle pricing from Maker, suggesting its launch may not be too far off.

‘Vaults’ are Yearn Finance’s core product. They use smart contracts to mobilize pooled assets from users to pursue arbitrage and yield farming strategies while sharing fees to mitigate gas costs.

As with Yearn’s recently launched Wrapped Ethereum (WETH) Vault, the WBTC Vault will leverage DAI minted against user holdings, which are then delegated to the protocol’s DAI Vault and mobilized to generate yield.

While Yearn’s Ether Vault saw deposits suspended after roughly $70 million worth ETH was delegated within days of its launch in early September, the returns generated by Yearn’s Vaults have fallen sharply in recent days.

Two weeks ago, Yearn’s ETH Vault was producing a weekly annualized percentage yield (APY) of more than 50%, while the DAI Vault offered 80% APY. As of this writing, the DAI Vault is generating a weekly APY of 30%, while the returns offered by the ETH Vault have plummeted 95% to post a weekly return equivalent to just 2% a year.

On September 18, Yearn Finance introduced its new ‘SyntheticRebaseDollar’, comprising “a credit based rebase index.” The index is intended to track the value of underlying assets against which a stablecoin has been minted, and automatically increases or decreases the sum of outstanding minted stablecoins in response to price fluctuations.

The team stated that they are “not yet sure” what they will use the protocol for, and wanted to publish the index so that others can build with and advance the technology.