{
  "$schema": "https://degreesofsatoshi.com/encyclopedia/schemas/article-v1.json",
  "schemaVersion": "1.0.0",
  "id": "what-is-susds",
  "canonical": "https://degreesofsatoshi.com/encyclopedia/what-is-susds/",
  "collection": "stablecoins",
  "title": "What is sUSDS? Shares in a USDS savings arrangement",
  "description": "Understand Sky’s savings USDS token as a vault share, including rate accumulation, conversion into USDS and authorized contract controls.",
  "aliases": [
    "sUSDS",
    "Savings USDS"
  ],
  "dates": {
    "published": "2026-10-02",
    "modified": "2026-10-02",
    "verified": "2026-10-02T18:15:23.891Z",
    "dataAsOf": "2026-10-02"
  },
  "authorship": {
    "publisher": "Degrees of Satoshi editorial project",
    "process": "AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied."
  },
  "quickAnswer": {
    "text": "sUSDS is the ERC-4626-compatible savings share for USDS in the Sky system. Its share-to-asset conversion reflects the savings-rate accumulator. It is distinct from plain USDS: the rate, contract authority, backing and available exit paths all matter, and a rising USDS-denominated ratio is not a guaranteed dollar return.",
    "claimId": "what-is-susds-quick-answer",
    "sourceIds": [
      "sky-savings",
      "sky-savings-code",
      "eip4626"
    ]
  },
  "keyFacts": [
    {
      "label": "Standard",
      "value": "Sky documents an ERC-4626-compatible deposit and withdrawal interface.",
      "sourceIds": [
        "sky-savings"
      ],
      "id": "standard",
      "claimId": "what-is-susds-fact-standard"
    },
    {
      "label": "Accounting",
      "value": "The implementation uses an accumulator and a savings-rate parameter.",
      "sourceIds": [
        "sky-savings-code"
      ],
      "id": "accounting",
      "claimId": "what-is-susds-fact-accounting"
    },
    {
      "label": "Upgradeability",
      "value": "The cited design uses a UUPS upgrade pattern.",
      "sourceIds": [
        "sky-savings"
      ],
      "id": "upgradeability",
      "claimId": "what-is-susds-fact-upgradeability"
    }
  ],
  "prerequisites": [
    "dai-and-usds"
  ],
  "sections": [
    {
      "id": "units",
      "heading": "Read shares and underlying USDS separately",
      "sourceIds": [
        "sky-savings",
        "eip4626"
      ],
      "paragraphs": [
        "A deposit exchanges underlying USDS for shares according to the vault’s accounting and rounding. Later, a share can represent a different amount of USDS as the rate accumulator changes.",
        "The share count in a wallet need not increase for the underlying claim to accrue. This differs from a token that directly rebases the displayed balance."
      ]
    },
    {
      "id": "rate",
      "heading": "A current parameter is not a lifetime promise",
      "sourceIds": [
        "sky-savings-code"
      ],
      "paragraphs": [
        "The cited implementation exposes authorized parameter-setting logic and rate accumulation. A rate displayed today should be dated and matched to the deployed version.",
        "A worked conversion is useful for understanding the mechanism, but this article intentionally does not quote a current annual return without a fresh verified parameter observation."
      ]
    },
    {
      "id": "dependencies",
      "heading": "Include the underlying asset and upgrade path",
      "sourceIds": [
        "sky-savings",
        "eip4626"
      ],
      "paragraphs": [
        "The savings position depends on USDS and on the savings contract’s rules. The documented upgradeability means readers should inspect the actual authority and current implementation.",
        "A share conversion function does not by itself establish secondary-market liquidity or remove the need to inspect withdrawal conditions and the underlying system’s risks."
      ]
    }
  ],
  "faq": [
    {
      "question": "Is sUSDS the same token as USDS?",
      "answer": "No. USDS is the underlying asset in this savings interface; sUSDS represents the vault-share position that can be converted under the contract’s rules.",
      "sourceIds": [
        "sky-savings",
        "eip4626"
      ]
    }
  ],
  "claims": [
    {
      "id": "what-is-susds-quick-answer",
      "articleSlug": "what-is-susds",
      "statement": "sUSDS is the ERC-4626-compatible savings share for USDS in the Sky system. Its share-to-asset conversion reflects the savings-rate accumulator. It is distinct from plain USDS: the rate, contract authority, backing and available exit paths all matter, and a rising USDS-denominated ratio is not a guaranteed dollar return.",
      "sourceIds": [
        "source-99c494fb0f9d448b",
        "source-65e5b82a59b99eee",
        "source-0500eb916f66cd39"
      ],
      "sourceLocators": [
        {
          "sourceId": "source-99c494fb0f9d448b",
          "locator": "sUSDS (Savings USDS); Details"
        },
        {
          "sourceId": "source-65e5b82a59b99eee",
          "locator": "ssr; file; drip; convertToAssets"
        },
        {
          "sourceId": "source-0500eb916f66cd39",
          "locator": "Specification; Security Considerations"
        }
      ],
      "scope": {
        "collection": "stablecoins",
        "dataAsOf": "2026-10-02",
        "blockHeight": null
      },
      "qualification": "",
      "evidenceStatus": "documented",
      "verification": {
        "status": "verified",
        "method": "independent automated source review",
        "checkedAt": "2026-10-02T18:15:23.891Z",
        "reviewer": "Independent automated verification agent verify_bitcoin_stablecoins_100",
        "notes": [
          "Read Sky Details, ERC-4626 shares/conversion requirements and pinned SUsds.sol auth, file(ssr), drip and convertToAssets. Conversion updates can reflect elapsed time without a recent drip call.",
          "Changed unsupported governance-controlled description to authorized contract controls: auth code does not identify every live authority. No current rate, implementation address or guaranteed dollar return is asserted."
        ]
      }
    },
    {
      "id": "what-is-susds-fact-standard",
      "articleSlug": "what-is-susds",
      "statement": "Standard: Sky documents an ERC-4626-compatible deposit and withdrawal interface.",
      "sourceIds": [
        "source-99c494fb0f9d448b"
      ],
      "sourceLocators": [
        {
          "sourceId": "source-99c494fb0f9d448b",
          "locator": "sUSDS (Savings USDS); Details"
        }
      ],
      "scope": {
        "collection": "stablecoins",
        "dataAsOf": "2026-10-02",
        "blockHeight": null
      },
      "qualification": "",
      "evidenceStatus": "documented",
      "verification": {
        "status": "verified",
        "method": "independent automated source review",
        "checkedAt": "2026-10-02T18:15:23.891Z",
        "reviewer": "Independent automated verification agent verify_bitcoin_stablecoins_100",
        "notes": [
          "Read Sky Details, ERC-4626 shares/conversion requirements and pinned SUsds.sol auth, file(ssr), drip and convertToAssets. Conversion updates can reflect elapsed time without a recent drip call.",
          "Changed unsupported governance-controlled description to authorized contract controls: auth code does not identify every live authority. No current rate, implementation address or guaranteed dollar return is asserted."
        ]
      }
    },
    {
      "id": "what-is-susds-fact-accounting",
      "articleSlug": "what-is-susds",
      "statement": "Accounting: The implementation uses an accumulator and a savings-rate parameter.",
      "sourceIds": [
        "source-65e5b82a59b99eee"
      ],
      "sourceLocators": [
        {
          "sourceId": "source-65e5b82a59b99eee",
          "locator": "ssr; file; drip; convertToAssets"
        }
      ],
      "scope": {
        "collection": "stablecoins",
        "dataAsOf": "2026-10-02",
        "blockHeight": null
      },
      "qualification": "",
      "evidenceStatus": "documented",
      "verification": {
        "status": "verified",
        "method": "independent automated source review",
        "checkedAt": "2026-10-02T18:15:23.891Z",
        "reviewer": "Independent automated verification agent verify_bitcoin_stablecoins_100",
        "notes": [
          "Read Sky Details, ERC-4626 shares/conversion requirements and pinned SUsds.sol auth, file(ssr), drip and convertToAssets. Conversion updates can reflect elapsed time without a recent drip call.",
          "Changed unsupported governance-controlled description to authorized contract controls: auth code does not identify every live authority. No current rate, implementation address or guaranteed dollar return is asserted."
        ]
      }
    },
    {
      "id": "what-is-susds-fact-upgradeability",
      "articleSlug": "what-is-susds",
      "statement": "Upgradeability: The cited design uses a UUPS upgrade pattern.",
      "sourceIds": [
        "source-99c494fb0f9d448b"
      ],
      "sourceLocators": [
        {
          "sourceId": "source-99c494fb0f9d448b",
          "locator": "sUSDS (Savings USDS); Details"
        }
      ],
      "scope": {
        "collection": "stablecoins",
        "dataAsOf": "2026-10-02",
        "blockHeight": null
      },
      "qualification": "",
      "evidenceStatus": "documented",
      "verification": {
        "status": "verified",
        "method": "independent automated source review",
        "checkedAt": "2026-10-02T18:15:23.891Z",
        "reviewer": "Independent automated verification agent verify_bitcoin_stablecoins_100",
        "notes": [
          "Read Sky Details, ERC-4626 shares/conversion requirements and pinned SUsds.sol auth, file(ssr), drip and convertToAssets. Conversion updates can reflect elapsed time without a recent drip call.",
          "Changed unsupported governance-controlled description to authorized contract controls: auth code does not identify every live authority. No current rate, implementation address or guaranteed dollar return is asserted."
        ]
      }
    }
  ],
  "sources": [
    {
      "id": "sky-savings",
      "label": "Sky Savings Rate",
      "publisher": "Sky",
      "url": "https://developers.skyeco.com/protocol/tokens/susds/",
      "locator": "sUSDS (Savings USDS); Details",
      "note": "Savings-share interface and upgradeable design; parameter values and deployed authority require separate evidence.",
      "version": null,
      "checkedAt": "2026-10-02T17:06:51.378Z",
      "contentSha256": "716dfc8908869b68eaf9041894aa1e6e46abc71f19181e89f89ac5955a6a8831",
      "recordId": "source-99c494fb0f9d448b"
    },
    {
      "id": "sky-savings-code",
      "label": "Savings USDS implementation",
      "publisher": "Sky contributors",
      "url": "https://raw.githubusercontent.com/sky-ecosystem/sdai/dfc7f41cb7599afcb0f0eb1ddaadbf9dd4015dce/src/SUsds.sol",
      "locator": "ssr; file; drip; convertToAssets",
      "note": "Savings-rate accumulator, administrator-set rate and share conversions.",
      "version": "susds implementation at dfc7f41cb7599afcb0f0eb1ddaadbf9dd4015dce",
      "checkedAt": "2026-10-02T17:41:56.801Z",
      "contentSha256": "9fe0c713751142e75a1da60ad6c0127d5ad01cb6d24289183ac48b202f3c5d69",
      "recordId": "source-65e5b82a59b99eee"
    },
    {
      "id": "eip4626",
      "label": "Tokenized Vaults",
      "publisher": "Ethereum Improvement Proposals",
      "url": "https://eips.ethereum.org/EIPS/eip-4626",
      "locator": "Specification; Security Considerations",
      "note": "Assets, shares, deposits, withdrawals, limits and preview rounding.",
      "version": "EIP/ERC-4626; retrieved document hash recorded",
      "checkedAt": "2026-10-02T17:03:42.366Z",
      "contentSha256": "0f3b3abdb9e37ef4094f0ad5c6c469a56e888fcc52415d4bf8e657e2b34792ab",
      "recordId": "source-0500eb916f66cd39"
    }
  ],
  "related": {
    "articles": [
      "dai-and-usds",
      "vault-share-price",
      "protocol-upgrades-and-admin-powers"
    ],
    "dossiers": [],
    "wallets": []
  },
  "revisionHistory": [
    {
      "date": "2026-10-02",
      "kind": "published",
      "summary": "First publication after primary-source research and independent automated verification."
    }
  ],
  "citation": "Degrees of Satoshi editorial project. “What is sUSDS? Shares in a USDS savings arrangement.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/what-is-susds/"
}