diff --git a/internal/api/v2/common.go b/internal/api/v2/common.go
index 06e2b7e09..8cceeea13 100644
--- a/internal/api/v2/common.go
+++ b/internal/api/v2/common.go
@@ -3,7 +3,9 @@ package v2
 import (
 	"io"
 	"net/http"
+	"slices"
 	"strconv"
+	"strings"
 
 	"github.com/formancehq/go-libs/api"
 
@@ -12,7 +14,6 @@ import (
 	"github.com/formancehq/go-libs/bun/bunpaginate"
 	"github.com/formancehq/go-libs/time"
 
-	"github.com/formancehq/go-libs/collectionutils"
 	"github.com/formancehq/go-libs/pointer"
 	"github.com/formancehq/go-libs/query"
 )
@@ -70,11 +71,21 @@ func getPITFilterWithVolumes(r *http.Request) (*ledgercontroller.PITFilterWithVo
 	}
 	return &ledgercontroller.PITFilterWithVolumes{
 		PITFilter:              *pit,
-		ExpandVolumes:          collectionutils.Contains(r.URL.Query()["expand"], "volumes"),
-		ExpandEffectiveVolumes: collectionutils.Contains(r.URL.Query()["expand"], "effectiveVolumes"),
+		ExpandVolumes:          hasExpandVolumes(r),
+		ExpandEffectiveVolumes: hasExpandEffectiveVolumes(r),
 	}, nil
 }
 
+func hasExpandVolumes(r *http.Request) bool {
+	parts := strings.Split(r.URL.Query().Get("expand"), ",")
+	return slices.Contains(parts, "volumes")
+}
+
+func hasExpandEffectiveVolumes(r *http.Request) bool {
+	parts := strings.Split(r.URL.Query().Get("expand"), ",")
+	return slices.Contains(parts, "effectiveVolumes")
+}
+
 func getFiltersForVolumes(r *http.Request) (*ledgercontroller.FiltersForVolumes, error) {
 	pit, err := getPITOOTFilter(r)
 	if err != nil {
diff --git a/internal/api/v2/controllers_accounts_read.go b/internal/api/v2/controllers_accounts_read.go
index 932782616..22259ab0e 100644
--- a/internal/api/v2/controllers_accounts_read.go
+++ b/internal/api/v2/controllers_accounts_read.go
@@ -5,7 +5,6 @@ import (
 	"net/url"
 
 	"github.com/formancehq/go-libs/api"
-	"github.com/formancehq/go-libs/collectionutils"
 	"github.com/formancehq/go-libs/platform/postgres"
 	"github.com/formancehq/ledger/internal/api/common"
 	ledgercontroller "github.com/formancehq/ledger/internal/controller/ledger"
@@ -22,10 +21,10 @@ func readAccount(w http.ResponseWriter, r *http.Request) {
 	}
 
 	query := ledgercontroller.NewGetAccountQuery(param)
-	if collectionutils.Contains(r.URL.Query()["expand"], "volumes") {
+	if hasExpandVolumes(r) {
 		query = query.WithExpandVolumes()
 	}
-	if collectionutils.Contains(r.URL.Query()["expand"], "effectiveVolumes") {
+	if hasExpandEffectiveVolumes(r) {
 		query = query.WithExpandEffectiveVolumes()
 	}
 	pitFilter, err := getPITFilter(r)
diff --git a/internal/api/v2/controllers_transactions_read.go b/internal/api/v2/controllers_transactions_read.go
index 39e652ee2..936f20a1d 100644
--- a/internal/api/v2/controllers_transactions_read.go
+++ b/internal/api/v2/controllers_transactions_read.go
@@ -5,7 +5,6 @@ import (
 	"strconv"
 
 	"github.com/formancehq/go-libs/api"
-	"github.com/formancehq/go-libs/collectionutils"
 	"github.com/formancehq/go-libs/platform/postgres"
 	"github.com/formancehq/ledger/internal/api/common"
 	ledgercontroller "github.com/formancehq/ledger/internal/controller/ledger"
@@ -22,10 +21,10 @@ func readTransaction(w http.ResponseWriter, r *http.Request) {
 	}
 
 	query := ledgercontroller.NewGetTransactionQuery(int(txId))
-	if collectionutils.Contains(r.URL.Query()["expand"], "volumes") {
+	if hasExpandVolumes(r) {
 		query = query.WithExpandVolumes()
 	}
-	if collectionutils.Contains(r.URL.Query()["expand"], "effectiveVolumes") {
+	if hasExpandEffectiveVolumes(r) {
 		query = query.WithExpandEffectiveVolumes()
 	}
 
diff --git a/openapi.yaml b/openapi.yaml
index 7dc40921c..5d053c608 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -3228,6 +3228,9 @@ components:
     V2Transaction:
       type: object
       properties:
+        insertedAt:
+          type: string
+          format: date-time
         timestamp:
           type: string
           format: date-time
@@ -3249,21 +3252,23 @@ components:
         revertedAt:
           type: string
           format: date-time
+        preCommitVolumes:
+          $ref: '#/components/schemas/V2AggregatedVolumes'
+        postCommitVolumes:
+          $ref: '#/components/schemas/V2AggregatedVolumes'
+        preCommitEffectiveVolumes:
+          $ref: '#/components/schemas/V2AggregatedVolumes'
+        postCommitEffectiveVolumes:
+          $ref: '#/components/schemas/V2AggregatedVolumes'
       required:
         - postings
         - timestamp
         - id
         - metadata
         - reverted
+        - insertedAt
     V2ExpandedTransaction:
-      allOf:
-        - $ref: '#/components/schemas/V2Transaction'
-        - type: object
-          properties:
-            preCommitVolumes:
-              $ref: '#/components/schemas/V2AggregatedVolumes'
-            postCommitVolumes:
-              $ref: '#/components/schemas/V2AggregatedVolumes'
+      $ref: '#/components/schemas/V2Transaction'
     V2PostTransaction:
       type: object
       required:
diff --git a/test/e2e/integration_test.go b/test/e2e/integration_test.go
index f5f5b1222..5d407c2bf 100644
--- a/test/e2e/integration_test.go
+++ b/test/e2e/integration_test.go
@@ -167,15 +167,21 @@ var _ = Context("Ledger integration tests", func() {
 						transactionFromAPI, err := GetTransaction(ctx, testServer.GetValue(), operations.V2GetTransactionRequest{
 							Ledger: createLedgerRequest.Ledger,
 							ID:     tx.ID,
+							Expand: pointer.For("volumes,effectiveVolumes"),
 						})
 						Expect(err).To(BeNil())
 						Expect(&components.V2Transaction{
-							Timestamp: transactionFromAPI.Timestamp,
-							Postings:  transactionFromAPI.Postings,
-							Reference: transactionFromAPI.Reference,
-							Metadata:  transactionFromAPI.Metadata,
-							ID:        transactionFromAPI.ID,
-							Reverted:  transactionFromAPI.Reverted,
+							InsertedAt:                 transactionFromAPI.InsertedAt,
+							Timestamp:                  transactionFromAPI.Timestamp,
+							Postings:                   transactionFromAPI.Postings,
+							Reference:                  transactionFromAPI.Reference,
+							Metadata:                   transactionFromAPI.Metadata,
+							ID:                         transactionFromAPI.ID,
+							Reverted:                   transactionFromAPI.Reverted,
+							PreCommitEffectiveVolumes:  transactionFromAPI.PreCommitEffectiveVolumes,
+							PostCommitEffectiveVolumes: transactionFromAPI.PostCommitEffectiveVolumes,
+							PreCommitVolumes:           transactionFromAPI.PreCommitVolumes,
+							PostCommitVolumes:          transactionFromAPI.PostCommitVolumes,
 						}).To(Equal(tx))
 					})
 				})