diff --git a/abis/IssuanceAllocator.json b/abis/IssuanceAllocator.json
new file mode 100644
index 00000000..40b5b5fa
--- /dev/null
+++ b/abis/IssuanceAllocator.json
@@ -0,0 +1,46 @@
+[
+  {
+    "anonymous": false,
+    "inputs": [
+      { "indexed": true, "internalType": "address", "name": "target", "type": "address" },
+      { "indexed": false, "internalType": "uint256", "name": "newAllocatorMintingRate", "type": "uint256" },
+      { "indexed": false, "internalType": "uint256", "name": "newSelfMintingRate", "type": "uint256" }
+    ],
+    "name": "TargetAllocationUpdated",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      { "indexed": false, "internalType": "uint256", "name": "oldIssuancePerBlock", "type": "uint256" },
+      { "indexed": false, "internalType": "uint256", "name": "newIssuancePerBlock", "type": "uint256" }
+    ],
+    "name": "IssuancePerBlockUpdated",
+    "type": "event"
+  },
+  {
+    "inputs": [],
+    "name": "getIssuancePerBlock",
+    "outputs": [{ "internalType": "uint256", "name": "", "type": "uint256" }],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [{ "internalType": "address", "name": "target", "type": "address" }],
+    "name": "getTargetAllocation",
+    "outputs": [
+      {
+        "components": [
+          { "internalType": "uint256", "name": "totalAllocationRate", "type": "uint256" },
+          { "internalType": "uint256", "name": "allocatorMintingRate", "type": "uint256" },
+          { "internalType": "uint256", "name": "selfMintingRate", "type": "uint256" }
+        ],
+        "internalType": "struct IIssuanceAllocationStatus.Allocation",
+        "name": "",
+        "type": "tuple"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  }
+]
diff --git a/abis/RewardsManagerStitched.json b/abis/RewardsManagerStitched.json
index 4c58dd58..3efbe0ce 100644
--- a/abis/RewardsManagerStitched.json
+++ b/abis/RewardsManagerStitched.json
@@ -603,5 +603,31 @@
     ],
     "stateMutability": "nonpayable",
     "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "getAllocatedIssuancePerBlock",
+    "outputs": [
+      {
+        "internalType": "uint256",
+        "name": "",
+        "type": "uint256"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "getIssuanceAllocator",
+    "outputs": [
+      {
+        "internalType": "address",
+        "name": "",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
   }
-]
+]
\ No newline at end of file
diff --git a/config/addresses.template.ts b/config/addresses.template.ts
index 94537328..8c0ff97c 100644
--- a/config/addresses.template.ts
+++ b/config/addresses.template.ts
@@ -22,6 +22,7 @@ export class Addresses {
   l2GraphTokenGateway: string
   ethereumDIDRegistry: string
   subgraphService: string
+  issuanceAllocator: string
   graphPayments: string
   paymentsEscrow: string
   graphTallyCollector: string
@@ -52,6 +53,7 @@ export let addresses: Addresses = {
   l2GraphTokenGateway: '{{l2GraphTokenGateway}}',
   ethereumDIDRegistry: '{{ethereumDIDRegistry}}',
   subgraphService: '{{subgraphService}}',
+  issuanceAllocator: '{{issuanceAllocator}}',
   graphPayments: '{{graphPayments}}',
   paymentsEscrow: '{{paymentsEscrow}}',
   graphTallyCollector: '{{graphTallyCollector}}',
diff --git a/config/arbitrumSepoliaAddressScript.ts b/config/arbitrumSepoliaAddressScript.ts
index 378cfae0..5b2913ea 100644
--- a/config/arbitrumSepoliaAddressScript.ts
+++ b/config/arbitrumSepoliaAddressScript.ts
@@ -5,6 +5,7 @@ import { Addresses } from './addresses.template'
 
 const horizonAddresses = require('@graphprotocol/address-book/horizon/addresses.json')
 const subgraphServiceAddresses = require('@graphprotocol/address-book/subgraph-service/addresses.json')
+const issuanceAddresses = require('@graphprotocol/address-book/issuance/addresses.json')
 
 // mustache doesn't like numbered object keys
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -15,10 +16,15 @@ renameHorizonAddresses['arbsep'] = horizonAddresses['421614']
 let renameSubgraphServiceAddresses: any = subgraphServiceAddresses
 renameSubgraphServiceAddresses['arbsep'] = subgraphServiceAddresses['421614']
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+let renameIssuanceAddresses: any = issuanceAddresses
+renameIssuanceAddresses['arbsep'] = issuanceAddresses['421614'] || {}
+
 const combinedAddresses = {
   arbsep: {
     ...renameHorizonAddresses['arbsep'],
-    ...renameSubgraphServiceAddresses['arbsep']
+    ...renameSubgraphServiceAddresses['arbsep'],
+    ...renameIssuanceAddresses['arbsep']
   }
 }
 
@@ -45,6 +51,7 @@ export let addresses: Addresses = {
   l2GraphTokenGateway: '{{arbsep.L2GraphTokenGateway.address}}',
   ethereumDIDRegistry: '{{arbsep.EthereumDIDRegistry.address}}',
   subgraphService: '{{arbsep.SubgraphService.address}}',
+  issuanceAllocator: '{{arbsep.IssuanceAllocator.address}}',
   graphPayments: '{{arbsep.GraphPayments.address}}',
   paymentsEscrow: '{{arbsep.PaymentsEscrow.address}}',
   graphTallyCollector: '{{arbsep.GraphTallyCollector.address}}',
diff --git a/config/localNetworkAddressScript.ts b/config/localNetworkAddressScript.ts
index 0efd624b..ee55619c 100644
--- a/config/localNetworkAddressScript.ts
+++ b/config/localNetworkAddressScript.ts
@@ -10,6 +10,7 @@ import { Addresses } from './addresses.template'
 let renameAddresses: any = {
   horizon: horizonAddresses['1337'],
   subgraphService: subgraphServiceAddresses['1337'],
+  issuanceAllocator: '0x0000000000000000000000000000000000000000',   // IssuanceAllocator is only deployed on Arbitrum
 }
 
 export let addresses: Addresses = {
diff --git a/config/mainnetArbitrumAddressScript.ts b/config/mainnetArbitrumAddressScript.ts
index a61504bc..cc848da9 100644
--- a/config/mainnetArbitrumAddressScript.ts
+++ b/config/mainnetArbitrumAddressScript.ts
@@ -4,6 +4,7 @@ import { Addresses } from './addresses.template'
 
 const horizonAddresses = require('@graphprotocol/address-book/horizon/addresses.json')
 const subgraphServiceAddresses = require('@graphprotocol/address-book/subgraph-service/addresses.json')
+const issuanceAddresses = require('@graphprotocol/address-book/issuance/addresses.json')
 
 // mustache doesn't like numbered object keys
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -14,10 +15,15 @@ renameHorizonAddresses['arbitrum'] = horizonAddresses['42161'] || {}
 let renameSubgraphServiceAddresses: any = subgraphServiceAddresses
 renameSubgraphServiceAddresses['arbitrum'] = subgraphServiceAddresses['42161'] || {}
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+let renameIssuanceAddresses: any = issuanceAddresses
+renameIssuanceAddresses['arbitrum'] = issuanceAddresses['42161'] || {}
+
 const combinedAddresses = {
   arbitrum: {
     ...renameHorizonAddresses['arbitrum'],
-    ...renameSubgraphServiceAddresses['arbitrum']
+    ...renameSubgraphServiceAddresses['arbitrum'],
+    ...renameIssuanceAddresses['arbitrum']
   }
 }
 
@@ -44,6 +50,7 @@ export let addresses: Addresses = {
   l2GraphTokenGateway: '{{arbitrum.L2GraphTokenGateway.address}}',
   ethereumDIDRegistry: '{{arbitrum.IEthereumDIDRegistry.address}}',
   subgraphService: '{{arbitrum.SubgraphService.address}}',
+  issuanceAllocator: '{{arbitrum.IssuanceAllocator.address}}',
   graphPayments: '{{arbitrum.GraphPayments.address}}',
   paymentsEscrow: '{{arbitrum.PaymentsEscrow.address}}',
   graphTallyCollector: '{{arbitrum.GraphTallyCollector.address}}',
diff --git a/config/testAddressesL1.ts b/config/testAddressesL1.ts
index 8de91df5..23741222 100644
--- a/config/testAddressesL1.ts
+++ b/config/testAddressesL1.ts
@@ -44,6 +44,7 @@ export let addresses: Addresses = {
   l2GraphTokenGateway: '',
   ethereumDIDRegistry: '0x0000000000000000000000000000000000000000',
   subgraphService: '0x0000000000000000000000000000000000000000',
+  issuanceAllocator: '0x0000000000000000000000000000000000000000',
   graphPayments: '0x0000000000000000000000000000000000000000',
   paymentsEscrow: '0x0000000000000000000000000000000000000000',
   graphTallyCollector: '0x0000000000000000000000000000000000000000',
diff --git a/config/testAddressesL2.ts b/config/testAddressesL2.ts
index ce8d1e34..10108fbe 100644
--- a/config/testAddressesL2.ts
+++ b/config/testAddressesL2.ts
@@ -44,6 +44,7 @@ export let addresses: Addresses = {
   l2GraphTokenGateway: '0x0000000000000000000000000000000000000000',
   ethereumDIDRegistry: '0x0000000000000000000000000000000000000000',
   subgraphService: '0x0000000000000000000000000000000000000000',
+  issuanceAllocator: '0x0000000000000000000000000000000000000000',
   graphPayments: '0x0000000000000000000000000000000000000000',
   paymentsEscrow: '0x0000000000000000000000000000000000000000',
   graphTallyCollector: '0x0000000000000000000000000000000000000000',
diff --git a/package.json b/package.json
index dc5e698f..42d116fa 100644
--- a/package.json
+++ b/package.json
@@ -42,7 +42,7 @@
     "prepare:test-l2": "yarn && yarn prep:addresses:test:l2 && mustache ./config/generatedAddresses.json subgraph.template.yaml > subgraph.yaml && graph codegen --output-dir src/types/"
   },
   "devDependencies": {
-    "@graphprotocol/address-book": "1.1.0",
+    "@graphprotocol/address-book": "^1.3.0",
     "@graphprotocol/contracts": "6.2.0",
     "@graphprotocol/graph-cli": "0.97.0",
     "@graphprotocol/graph-ts": "0.36.0",
diff --git a/src/mappings/issuanceAllocator.ts b/src/mappings/issuanceAllocator.ts
new file mode 100644
index 00000000..9eb48910
--- /dev/null
+++ b/src/mappings/issuanceAllocator.ts
@@ -0,0 +1,34 @@
+import { TargetAllocationUpdated } from '../types/IssuanceAllocator/IssuanceAllocator'
+import { createOrLoadGraphNetwork } from './helpers/helpers'
+import { addresses } from '../../config/addresses'
+import { Address } from '@graphprotocol/graph-ts'
+
+/**
+ * @dev handleTargetAllocationUpdated
+ * - Keeps GraphNetwork.networkGRTIssuancePerBlock in step with the share of
+ *   issuance the RewardsManager actually receives.
+ *
+ * Since GIP-0076/GIP-0088 the RewardsManager no longer owns the issuance rate:
+ * the IssuanceAllocator splits total issuance across targets and the
+ * RewardsManager mints only its own allocation. GIP-0089 exercised that for the
+ * first time on 2026-09-01, moving 24.146 GRT/block (20%) to the Foundation's
+ * Innovation Allocation and leaving the RewardsManager 96.584 of the unchanged
+ * 120.73 total.
+ *
+ * That change is invisible to the RewardsManager's own ParameterUpdated event,
+ * so without this handler networkGRTIssuancePerBlock stays at whatever the
+ * legacy `issuancePerBlock` storage slot last held — 120.73 — and every
+ * downstream APR calculation built on it overstates indexing rewards by 25%.
+ *
+ * The RewardsManager is an allocator target that mints its own issuance, so
+ * `newSelfMintingRate` is the rate it will issue at. The event carries it, so
+ * no contract call is needed here.
+ */
+export function handleTargetAllocationUpdated(event: TargetAllocationUpdated): void {
+  if (event.params.target != Address.fromString(addresses.rewardsManager)) {
+    return
+  }
+  let graphNetwork = createOrLoadGraphNetwork(event.block.number, event.address)
+  graphNetwork.networkGRTIssuancePerBlock = event.params.newSelfMintingRate
+  graphNetwork.save()
+}
diff --git a/src/mappings/rewardsManager.ts b/src/mappings/rewardsManager.ts
index d66f33ed..52c29327 100644
--- a/src/mappings/rewardsManager.ts
+++ b/src/mappings/rewardsManager.ts
@@ -69,7 +69,16 @@ export function handleParameterUpdated(event: ParameterUpdated): void {
   if (parameter == 'issuanceRate') {
     graphNetwork.networkGRTIssuance = rewardsManager.issuanceRate()
   } else if (parameter == 'issuancePerBlock') {
-    graphNetwork.networkGRTIssuancePerBlock = rewardsManager.issuancePerBlock()
+    // Read the allocator-aware rate, not the legacy `issuancePerBlock` slot.
+    // Since the IssuanceAllocator was wired up (GIP-0088) the RewardsManager
+    // issues only its own allocation, and the legacy slot is no longer that
+    // number — on Arbitrum it still reads 120.73 while the allocated rate is
+    // 96.584. try_ so the call is safe on deployments predating the upgrade,
+    // where the getter does not exist.
+    let allocated = rewardsManager.try_getAllocatedIssuancePerBlock()
+    graphNetwork.networkGRTIssuancePerBlock = allocated.reverted
+      ? rewardsManager.issuancePerBlock()
+      : allocated.value
   } else if (parameter == 'subgraphAvailabilityOracle') {
     graphNetwork.subgraphAvailabilityOracle = rewardsManager.subgraphAvailabilityOracle()
   }
diff --git a/subgraph.template.yaml b/subgraph.template.yaml
index 09ffddb4..601cff61 100644
--- a/subgraph.template.yaml
+++ b/subgraph.template.yaml
@@ -529,6 +529,31 @@ dataSources:
             EpochManager.blockNum: EpochManager[{{epochManager}}].blockNum()
         - event: AllowedLockedVerifierSet(indexed address,bool)
           handler: handleAllowedLockedVerifierSet
+  # The IssuanceAllocator owns the split of protocol issuance across targets
+  # (GIP-0076, deployed by GIP-0088). The RewardsManager is one target and mints
+  # only its own allocation, so this is the only place a change to the indexing
+  # reward rate is observable — the RewardsManager itself emits nothing when the
+  # split moves. Arbitrum only; the address resolves empty elsewhere.
+  - kind: ethereum/contract
+    name: IssuanceAllocator
+    network: {{network}}
+    source:
+      address: "{{issuanceAllocator}}"
+      abi: IssuanceAllocator
+      startBlock: {{blockNumber}}
+    mapping:
+      kind: ethereum/events
+      apiVersion: 0.0.9
+      language: wasm/assemblyscript
+      file: ./src/mappings/issuanceAllocator.ts
+      entities:
+        - GraphNetwork
+      abis:
+        - name: IssuanceAllocator
+          file: ./abis/IssuanceAllocator.json
+      eventHandlers:
+        - event: TargetAllocationUpdated(indexed address,uint256,uint256)
+          handler: handleTargetAllocationUpdated
   - kind: ethereum/contract
     name: SubgraphService
     network: {{network}}
diff --git a/yarn.lock b/yarn.lock
index 0f6cd4e1..034e1077 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -818,10 +818,10 @@
     graphql-import-node "^0.0.5"
     js-yaml "^4.1.0"
 
-"@graphprotocol/address-book@1.1.0":
-  version "1.1.0"
-  resolved "https://registry.npmjs.org/@graphprotocol/address-book/-/address-book-1.1.0.tgz"
-  integrity sha512-38NiutGOWdDIYgB/3kGp/7LxPRCNomipjo1hGlaj6RvyydySooVSmb3A+j84faUso+uhYxt8+9y1EFN7XVnT7Q==
+"@graphprotocol/address-book@^1.3.0":
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/@graphprotocol/address-book/-/address-book-1.3.0.tgz#234de18cd3931c309cf0385d46f88cc6d3a14355"
+  integrity sha512-rkrgBOOxM5WLNsoVrr6Gvg6DYvDes+P13vL5k1/QYWc5/z/G6pt4DBgzR/7wJV5xhIMevCumpg6L7ZuVQwS0ug==
 
 "@graphprotocol/common-ts@^2.0.7":
   version "2.0.11"