Sky is the ecosystem name, USDS is a stablecoin token, sUSDS represents a savings-vault position, and SKY is associated with protocol governance. The distinction matters because receiving one of these tokens does not provide the rights of the others. Official documentation specifies a one-for-one Dai-to-USDS converter with a reverse route. That conversion concerns units of two protocol tokens; it is not a promise that either trades at exactly one dollar on every exchange or that token conversion is a bank withdrawal.

sUSDS implements an ERC-4626 vault around USDS. Depositing assets produces shares, and redeeming shares withdraws the corresponding asset amount according to the vault's accounting. The Sky Savings Rate is reflected in the share-to-asset relationship rather than requiring every holder to receive a new token transfer for each increment. For an illustrative balance, the useful question is how much USDS a given number of shares currently represents. Comparing only the visible count of sUSDS units can miss changes in the value recorded by that relationship.

The USDS and sUSDS documentation identifies upgradeable contract designs, making control of upgrades part of the system's trust model. Separately, Sky's governance migration materials describe changes to the Chief voting contract, conversion direction for governance tokens, and possible delayed-upgrade penalties. Those terms should not be inferred from the simpler Dai-USDS conversion route: they concern different assets and authorities. A historical guide can explain the design while still being unsuitable for a current migration transaction.

The relevant contract addresses and active governance decisions provide the evidence for the current state.