> For the complete documentation index, see [llms.txt](https://docs.kpk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kpk.io/funds/infrastructure/onchain-accounting/price-feeds/ethx.md).

# ETHx

ETHx is Stader's liquid staked-ETH token. No direct ETHx/USD Chainlink feed is used; this `ICustomPriceFeed` adapter combines Stader's exchange rate with an ETH/USD price read from the NAV's own primary feed. An independent [cross-rate](/funds/infrastructure/onchain-accounting/price-feeds/cross-rate.md) **monitor** feed (`ETH/USD × ETHx/ETH`, with a **Chainlink** `ETHx/ETH` leg) is registered as a [divergence monitor](/funds/infrastructure/onchain-accounting/price-feeds.md#primary-feed-and-divergence-monitors) — a market depeg flags ETHx `irregular` without moving its price. That cross-rate is ETHx's **only** monitor: the direct Redstone `ETHx/USD` monitor was removed with no replacement when Redstone retired its ETHx push feeds, and Chainlink publishes no `ETHx/USD`. The cross-rate survived because its rate leg could be migrated from Redstone to Chainlink's `ETHx/ETH`, so ETHx keeps its 250 bps divergence signal.

{% hint style="info" %}
The ETH/USD term is sourced from the NAV's own selector — see [Base/USD from the NAV's own selector](/funds/infrastructure/onchain-accounting/price-feeds.md#base-usd-from-the-navs-own-selector).
{% endhint %}

**Source:** [`ETHx_CustomPriceFeed.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/prices/protocols/ETHx_CustomPriceFeed.sol)

***

## Approach

`getExchangeRate()` (StakePoolsManager) × ETH/USD.

<figure><img src="/files/0SKUuhwTdHzPRfrFLsEG" alt="Left-to-right flowchart of the ETHx price feed: rate and Chainlink inputs combine into a USD price, with a staleness gate."><figcaption><p>ETHx price feed — how its oracle inputs compose into a USD price, with the staleness gate.</p></figcaption></figure>

***

## Price calculation

```
price = getExchangeRate() (18) × (ETH/USD) (8) / 1e18      // USD, 8 dec
```

| Input             | Source                                                | Description                      |
| ----------------- | ----------------------------------------------------- | -------------------------------- |
| `getExchangeRate` | `IStaderStakePoolsManager.getExchangeRate()` (18 dec) | ETH per 1 ETHx                   |
| ETH/USD           | NAV base — `getPriceDataNoDivergence(WETH)` (8 dec)   | the NAV's primary WETH/USD price |

The rate is read from Stader's StakePoolsManager and grows as staking rewards accrue. The constructor additionally requires the manager address to be a deployed contract (non-zero `code.length`). Output decimals are inherited from the ETH/USD feed (8).

***

## Constructor

```solidity
constructor(
    address ethx_,
    address stakePoolsManager_,
    address nav_,
    address baseAsset_
)
```

| Parameter            | Description                                                                                |
| -------------------- | ------------------------------------------------------------------------------------------ |
| `ethx_`              | ETHx token address (also the supported underlying)                                         |
| `stakePoolsManager_` | Stader StakePoolsManager (exposes `getExchangeRate()`)                                     |
| `nav_`               | NAVCalculator (proxy) — supplies the base asset's USD price via `getPriceDataNoDivergence` |
| `baseAsset_`         | The registered base asset whose USD price is read (WETH)                                   |

***

## Staleness

`getLatestPrice()` returns stale if `getExchangeRate()` returns `0`, or 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 rate call has no independent heartbeat.

***

## Chains

Deployed on **Ethereum**.


---

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