diff --git a/x/vm/keeper/call_evm.go b/x/vm/keeper/call_evm.go
index 727f83a9b0..9f1314ddf6 100644
--- a/x/vm/keeper/call_evm.go
+++ b/x/vm/keeper/call_evm.go
@@ -260,8 +260,9 @@ func (k Keeper) DerivedEVMCallWithData(
 			sdk.NewAttribute(sdk.AttributeKeyAmount, value.String()),
 			// add event for ethereum transaction hash format;
 			sdk.NewAttribute(types.AttributeKeyEthereumTxHash, ethTxHash),
-			// add event for index of valid ethereum tx; NOTE: default txindex for derivedTx
-			sdk.NewAttribute(types.AttributeKeyTxIndex, strconv.FormatUint(types.DerivedTxIndex, 10)),
+			// unique, monotonic eth tx index for this derived tx — drawn from the same
+			// block-level counter as standard MsgEthereumTx (advanced below).
+			sdk.NewAttribute(types.AttributeKeyTxIndex, strconv.FormatUint(uint64(txConfig.TxIndex), 10)),
 			// add event for eth tx gas used, we can't get it from cosmos tx result when it contains multiple eth tx msgs.
 			sdk.NewAttribute(types.AttributeKeyTxGasUsed, strconv.FormatUint(gasUsed, 10)),
 		}...)
@@ -325,6 +326,10 @@ func (k Keeper) DerivedEVMCallWithData(
 				k.SetLogSizeTransient(ctx, (k.GetLogSizeTransient(ctx))+uint64(len(logs)))
 			}
 		}
+
+		// Advance the block-level eth tx index so the next eth tx (derived or a
+		// standard MsgEthereumTx) gets a fresh, unique index. Mirrors ApplyTransaction.
+		k.SetTxIndexTransient(ctx, uint64(txConfig.TxIndex)+1)
 	}
 
 	if res.Failed() {
diff --git a/x/vm/keeper/call_evm_test.go b/x/vm/keeper/call_evm_test.go
index 40ac08070e..73da98598d 100644
--- a/x/vm/keeper/call_evm_test.go
+++ b/x/vm/keeper/call_evm_test.go
@@ -3,6 +3,7 @@ package keeper_test
 import (
 	"fmt"
 	"math/big"
+	"strconv"
 
 	"github.com/ethereum/go-ethereum/common"
 
@@ -337,3 +338,43 @@ func (suite *KeeperTestSuite) TestDerivedEVMCallCommitFlag() {
 		})
 	}
 }
+
+// TestDerivedEVMCallAssignsUniqueTxIndex is a regression test for F-2026-17745:
+// each derived tx in a block must get a unique, monotonically increasing eth tx
+// index (not the legacy constant 9999 shared by all derived txs).
+func (suite *KeeperTestSuite) TestDerivedEVMCallAssignsUniqueTxIndex() {
+	suite.SetupTest()
+
+	owner := suite.keyring.GetAddr(0)
+	recipient := utiltx.GenerateAddress()
+
+	contractAddr := suite.DeployTestContract(suite.T(), suite.network.GetContext(), owner, big.NewInt(1_000_000))
+	ctx := suite.network.GetContext().WithEventManager(sdk.NewEventManager())
+
+	const n = 3
+	for i := 0; i < n; i++ {
+		suite.Require().NoError(suite.derivedTransfer(ctx, owner, contractAddr, recipient))
+	}
+
+	// Collect the txIndex attribute emitted on each ethereum_tx event.
+	var indices []uint64
+	for _, e := range ctx.EventManager().Events() {
+		if e.Type != evmtypes.EventTypeEthereumTx {
+			continue
+		}
+		for _, a := range e.Attributes {
+			if a.Key == evmtypes.AttributeKeyTxIndex {
+				v, err := strconv.ParseUint(a.Value, 10, 64)
+				suite.Require().NoError(err)
+				indices = append(indices, v)
+			}
+		}
+	}
+
+	suite.Require().Len(indices, n, "one txIndex per derived tx")
+	suite.Require().NotEqual(uint64(9999), indices[0], "must not use the legacy constant DerivedTxIndex")
+	for i := 1; i < len(indices); i++ {
+		suite.Require().Equal(indices[0]+uint64(i), indices[i],
+			"derived txs must get unique, monotonically increasing indices")
+	}
+}
diff --git a/x/vm/types/events.go b/x/vm/types/events.go
index 489635e41d..15e5ddf046 100644
--- a/x/vm/types/events.go
+++ b/x/vm/types/events.go
@@ -30,6 +30,5 @@ const (
 )
 
 const (
-	DerivedTxIndex = 9999
-	DerivedTxType  = 99
+	DerivedTxType = 99
 )