spETH

Custom price feed for Spark Savings ETH (spETH).

Custom price feed for Spark Savings ETH (spETH). spETH is an ERC-4626 vault share that accrues value as savings yield accumulates. The price is derived from the vault's current share-to-asset conversion rate multiplied by the NAV's WETH/USD price.

Source: spETH_CustomPriceFeed.sol

---

Approach

spETH.convertToAssets(1 spETH) × WETH/USD (from the NAV's primary feed)

The WETH/USD term is sourced from the NAV's own selector — see Base/USD from the NAV's own selector.

Spark shipped this savings family twice — pin the vault by address, never by symbol(). A dead earlier generation answers the same symbol() at a different address with totalSupply == 0. An empty ERC-4626 answers convertToAssets at the 1:1 default instead of reverting, so wiring the dead one prices plausibly and wrongly. Note that spETH is 18-decimal in both generations, so decimals alone does not disambiguate it — only the address does.

---

Price calculation

decimals = spETH.decimals()                     // vault share decimals
rate     = spETH.convertToAssets(10^decimals)   // WETH per 1 spETH
price    = rate × WETH_USD / 10^assetDecimals

Input	Source	Description
convertToAssets()	IERC4626(spETH)	WETH backing per 1 spETH share at the current accrued rate
WETH_USD	NAV base — getPriceDataNoDivergence(WETH) (8 dec)	the NAV's primary WETH/USD price

The divisor is 10^assetDecimals (the underlying's decimals), not the share decimals — they differ whenever a vault uses a decimals offset. Result carries the feed's 8 decimals.

---

Constructor

constructor(
    address vault_,
    address nav_,
    address baseAsset_
)

Parameter	Description
vault_	The spETH vault address (also used to read vault decimals)
nav_	NAVCalculator (proxy) — supplies the base asset's USD price via getPriceDataNoDivergence
baseAsset_	The registered base asset whose USD price is read (WETH); must equal the vault's asset() — reverts BaseAssetMismatch otherwise

---

Staleness

The price is stale if the NAV reports the base asset (WETH) stale — all its feeds stale. The base leg's updatedAt comes from the NAV's selected WETH feed. The convertToAssets rate has no heartbeat — it is a live view on the ERC-4626 vault.

---

Chains

Deployed on Ethereum mainnet only.

Unlike the other members of this family the base is WETH, not a stablecoin, so the share price tracks ETH rather than $1.