> 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/meta-balance-adapters/balancer-v2-pools.md).

# Balancer V2 Pools

Reports an account's **wallet-held (unstaked)** Balancer V2 pool liquidity across any pool. It decomposes the account's BPT balance pro-rata into the pool's underlying tokens by reading the Balancer V2 Vault's live balances — the AMM-supplied LP only. Gauge-staked LP and rewards are the separate [Balancer V2 Gauges](/funds/infrastructure/onchain-accounting/meta-balance-adapters/balancer-v2-gauges.md) adapter.

* **Type:** Meta-adapter
* **protocolSubId:** `keccak256("balancer-v2-pools")`
* **Instance key:** the pool's **raw `bytes32` poolId** (used directly, not an address). The BPT (ERC20) address is the top 160 bits of the poolId.
* **Source:** [`BalancerV2PoolsMetaBalanceAdapter.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/balances/MetaBalanceAdapters/balancer/BalancerV2PoolsMetaBalanceAdapter.sol)

***

## Positions returned

One leg per registered underlying pool token with a non-zero share:

| Leg    | PositionKind | isDebt  | Description                                                                |
| ------ | ------------ | ------- | -------------------------------------------------------------------------- |
| Supply | `Supplied`   | `false` | Pro-rata share of one underlying pool token, from the account's wallet BPT |

The pool's own pre-minted BPT (composable-stable pools) is excluded from the token list. Unregistered, zero-amount, and asset-filtered tokens are skipped.

***

## Balance calculation

<figure><img src="/files/XxouN4dBq6aO8XMGr9Cm" alt="Flowchart of the Balancer V2 Pools balance adapter: read calls derive position legs into PositionBalance entries."><figcaption><p>Balancer V2 Pools adapter — how the underlying balances reported to the NAV Calculator are derived.</p></figcaption></figure>

Balancer V2 holds every pool's tokens in a single Vault. For BPT balance `walletBpt = BPT.balanceOf(account)` (returns nothing if zero), `BalancerV2PoolLib.shares` reads the Vault's `getPoolTokens(poolId)` balances and computes each token's pro-rata amount:

```
amount[i] = balances[i] * walletBpt / effectiveSupply
```

`effectiveSupply` is `getActualSupply()` when the pool exposes it (composable-stable: excludes pre-minted BPT, includes due protocol fees) and falls back to `totalSupply()` for legacy weighted/stable pools.

***

## Identity

* **positionId:** `abi.encode(bytes32 poolId)`
* **positionKind:** `Supplied`

There is no `labels` field on the position. The adapter implements `positionLabels(positionId)`, which returns `["AMM Liquidity Pool", "<sym0>/<sym1>/…"]` from the pool's underlying token symbols — surfaced only by the verbose reads (`getAccountPositionsVerbose` / `getAccountNavVerbose`); the full breadcrumb is `[protocolName, ...labels]`.

***

## Constructor

```solidity
constructor(address vault_, address navCalculator_)
```

| Parameter        | Description                                                                                                  |
| ---------------- | ------------------------------------------------------------------------------------------------------------ |
| `vault_`         | Balancer V2 Vault address (must be a contract); the chain-level singleton that custodies every pool's tokens |
| `navCalculator_` | NAVCalculator address (must be a contract); source of the asset registry and the instance set                |

***

## Registration

Registered as a meta-adapter via `addMetaBalanceAdapter(adapter, instances)`, with the instance set adjusted by `addMetaInstances` / `removeMetaInstances`. Instance coordinates are passed as `bytes32` and stored as-is — for Balancer V2 each coordinate is the **raw `bytes32` poolId** (not an address widened to `bytes32`, as most meta-adapters use). The adapter recovers the BPT from the poolId's top 160 bits when it needs the ERC-20.


---

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