diff --git a/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp b/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
index 1452a4295817..254ab91d0af8 100644
--- a/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
+++ b/ydb/core/tx/schemeshard/schemeshard__table_stats.cpp
@@ -264,18 +264,19 @@ bool TTxStoreTableStats::PersistSingleStats(const TPathId& pathId,
                                                                subDomainInfo->EffectiveStoragePools(),
                                                                shardInfo->BindedChannels);
 
+    const auto pathElement = Self->PathsById[pathId];
     LOG_DEBUG_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
                 "TTxStoreTableStats.PersistSingleStats: main stats from"
                     << " datashardId(TabletID)=" << datashardId << " maps to shardIdx: " << shardIdx
-                    << ", pathId: " << pathId << ", pathId map=" << Self->PathsById[pathId]->Name
+                    << ", pathId: " << pathId << ", pathId map=" << pathElement->Name
                     << ", is column=" << isColumnTable << ", is olap=" << isOlapStore);
 
     const TPartitionStats newStats = PrepareStats(ctx, rec, channelsMapping);
 
     LOG_INFO_S(ctx, NKikimrServices::FLAT_TX_SCHEMESHARD,
-               "Add stats from shard with datashardId(TabletID)=" << datashardId 
+               "Add stats from shard with datashardId(TabletID)=" << datashardId
                     << ", pathId " << pathId.LocalPathId
-                    << ": RowCount " << newStats.RowCount 
+                    << ": RowCount " << newStats.RowCount
                     << ", DataSize " << newStats.DataSize
                     << (newStats.HasBorrowedData ? ", with borrowed parts" : ""));
 
@@ -404,11 +405,14 @@ bool TTxStoreTableStats::PersistSingleStats(const TPathId& pathId,
         Self->TabletCounters->Percentile()[COUNTER_NUM_SHARDS_BY_TTL_LAG].IncrementFor(lag->Seconds());
     }
 
+    const TTableIndexInfo* index = Self->Indexes.Value(pathElement->ParentPathId, nullptr).Get();
     const TTableInfo* mainTableForIndex = Self->GetMainTableForIndex(pathId);
 
     const auto forceShardSplitSettings = Self->SplitSettings.GetForceShardSplitSettings();
     TVector<TShardIdx> shardsToMerge;
-    if (table->CheckCanMergePartitions(Self->SplitSettings, forceShardSplitSettings, shardIdx, shardsToMerge, mainTableForIndex)) {
+    if ((!index || index->State == NKikimrSchemeOp::EIndexStateReady)
+        && table->CheckCanMergePartitions(Self->SplitSettings, forceShardSplitSettings, shardIdx, shardsToMerge, mainTableForIndex)
+    ) {
         TTxId txId = Self->GetCachedTxId(ctx);
 
         if (!txId) {
diff --git a/ydb/core/tx/schemeshard/ut_helpers/helpers.cpp b/ydb/core/tx/schemeshard/ut_helpers/helpers.cpp
index c4b2763d8f70..7fe813667928 100644
--- a/ydb/core/tx/schemeshard/ut_helpers/helpers.cpp
+++ b/ydb/core/tx/schemeshard/ut_helpers/helpers.cpp
@@ -16,6 +16,7 @@
 
 #include <ydb/core/util/pb.h>
 #include <ydb/public/api/protos/ydb_export.pb.h>
+#include <ydb/public/sdk/cpp/client/ydb_table/table.h>
 
 #include <library/cpp/testing/unittest/registar.h>
 
@@ -1679,12 +1680,18 @@ namespace NSchemeShardUT_Private {
         *index.mutable_data_columns() = {cfg.DataColumns.begin(), cfg.DataColumns.end()};
 
         switch (cfg.IndexType) {
-        case NKikimrSchemeOp::EIndexTypeGlobal:
-            *index.mutable_global_index() = Ydb::Table::GlobalIndex();
-            break;
-        case NKikimrSchemeOp::EIndexTypeGlobalAsync:
-            *index.mutable_global_async_index() = Ydb::Table::GlobalAsyncIndex();
-            break;
+        case NKikimrSchemeOp::EIndexTypeGlobal: {
+            auto& settings = *index.mutable_global_index()->mutable_settings();
+            if (cfg.GlobalIndexSettings) {
+                cfg.GlobalIndexSettings[0].SerializeTo(settings);
+            }
+        } break;
+        case NKikimrSchemeOp::EIndexTypeGlobalAsync: {
+            auto& settings = *index.mutable_global_async_index()->mutable_settings();
+            if (cfg.GlobalIndexSettings) {
+                cfg.GlobalIndexSettings[0].SerializeTo(settings);
+            }
+        } break;
         case NKikimrSchemeOp::EIndexTypeGlobalVectorKmeansTree: {
             auto& settings = *index.mutable_global_vector_kmeans_tree_index();
             settings = Ydb::Table::GlobalVectorKMeansTreeIndex();
@@ -2011,7 +2018,7 @@ namespace NSchemeShardUT_Private {
                 Runtime.SendToPipe(shardData.ShardId, sender, proposal);
                 TAutoPtr<IEventHandle> handle;
                 auto event = Runtime.GrabEdgeEventIf<TEvDataShard::TEvProposeTransactionResult>(handle,
-                                                                                                [=](const TEvDataShard::TEvProposeTransactionResult& event) {
+                                                                                                [this, shardData](const TEvDataShard::TEvProposeTransactionResult& event) {
                     return event.GetTxId() == TxId && event.GetOrigin() == shardData.ShardId;
                 });
                 activeZone = true;
diff --git a/ydb/core/tx/schemeshard/ut_helpers/helpers.h b/ydb/core/tx/schemeshard/ut_helpers/helpers.h
index 6b6b338ea79f..eb4feee35b56 100644
--- a/ydb/core/tx/schemeshard/ut_helpers/helpers.h
+++ b/ydb/core/tx/schemeshard/ut_helpers/helpers.h
@@ -62,6 +62,10 @@
     template<bool OPT1, bool OPT2>                                                                                 \
     void N(NUnitTest::TTestContext&)
 
+namespace NYdb::NTable {
+    struct TGlobalIndexSettings;
+}
+
 namespace NSchemeShardUT_Private {
     using namespace NKikimr;
 
@@ -361,6 +365,7 @@ namespace NSchemeShardUT_Private {
         NKikimrSchemeOp::EIndexType IndexType = NKikimrSchemeOp::EIndexTypeGlobal;
         TVector<TString> IndexColumns;
         TVector<TString> DataColumns;
+        TVector<NYdb::NTable::TGlobalIndexSettings> GlobalIndexSettings = {};
     };
 
     std::unique_ptr<TEvIndexBuilder::TEvCreateRequest> CreateBuildColumnRequest(ui64 id, const TString& dbName, const TString& src, const TString& columnName, const Ydb::TypedValue& literal);
diff --git a/ydb/core/tx/schemeshard/ut_helpers/ya.make b/ydb/core/tx/schemeshard/ut_helpers/ya.make
index 353849a5f51a..5eb4bf14ca88 100644
--- a/ydb/core/tx/schemeshard/ut_helpers/ya.make
+++ b/ydb/core/tx/schemeshard/ut_helpers/ya.make
@@ -22,6 +22,7 @@ PEERDIR(
     ydb/public/lib/scheme_types
     ydb/library/yql/public/issue
     ydb/public/sdk/cpp/client/ydb_driver
+    ydb/public/sdk/cpp/client/ydb_table
 )
 
 SRCS(
diff --git a/ydb/core/tx/schemeshard/ut_index/ut_async_index.cpp b/ydb/core/tx/schemeshard/ut_index/ut_async_index.cpp
index e96f9a0ac11d..7337b0a8a71c 100644
--- a/ydb/core/tx/schemeshard/ut_index/ut_async_index.cpp
+++ b/ydb/core/tx/schemeshard/ut_index/ut_async_index.cpp
@@ -5,6 +5,7 @@
 #include <ydb/core/tx/schemeshard/ut_helpers/test_with_reboots.h>
 #include <ydb/core/testlib/tablet_helpers.h>
 #include <ydb/public/lib/deprecated/kicli/kicli.h>
+#include <ydb/public/sdk/cpp/client/ydb_table/table.h>
 
 using namespace NKikimr;
 using namespace NSchemeShard;
@@ -574,5 +575,5 @@ Y_UNIT_TEST_SUITE(TAsyncIndexTests) {
       NLs::IndexState(NKikimrSchemeOp::EIndexStateReady),
       NLs::IndexKeys({"indexed"}),
         });
-    }    
+    }
 }
diff --git a/ydb/core/tx/schemeshard/ut_index_build/ut_index_build.cpp b/ydb/core/tx/schemeshard/ut_index_build/ut_index_build.cpp
index 4512e02ac601..5cf2ef6cb5c1 100644
--- a/ydb/core/tx/schemeshard/ut_index_build/ut_index_build.cpp
+++ b/ydb/core/tx/schemeshard/ut_index_build/ut_index_build.cpp
@@ -2,11 +2,15 @@
 #include <ydb/core/tx/scheme_board/events.h>
 #include <ydb/core/tx/schemeshard/ut_helpers/helpers.h>
 #include <ydb/core/tx/schemeshard/schemeshard_billing_helpers.h>
+#include <ydb/core/testlib/actors/block_events.h>
+#include <ydb/core/testlib/actors/wait_events.h>
 #include <ydb/core/testlib/tablet_helpers.h>
 
 #include <ydb/core/tx/datashard/datashard.h>
 #include <ydb/core/metering/metering.h>
 
+#include <ydb/public/sdk/cpp/client/ydb_table/table.h>
+
 using namespace NKikimr;
 using namespace NSchemeShard;
 using namespace NSchemeShardUT_Private;
@@ -781,6 +785,155 @@ Y_UNIT_TEST_SUITE(IndexBuildTest) {
 
     }
 
+    Y_UNIT_TEST(MergeIndexTableShardsOnlyWhenReady) {
+        TTestBasicRuntime runtime;
+
+        TTestEnvOptions opts;
+        opts.EnableBackgroundCompaction(false);
+        opts.DisableStatsBatching(true);
+        TTestEnv env(runtime, opts);
+
+        NDataShard::gDbStatsReportInterval = TDuration::Seconds(0);
+
+        ui64 txId = 100;
+
+        TestCreateTable(runtime, ++txId, "/MyRoot", R"(
+            Name: "Table"
+            Columns { Name: "key" Type: "Uint64" }
+            Columns { Name: "value" Type: "Uint64" }
+            KeyColumnNames: ["key"]
+        )");
+        env.TestWaitNotification(runtime, txId);
+
+        Ydb::Table::GlobalIndexSettings settings;
+        UNIT_ASSERT(google::protobuf::TextFormat::ParseFromString(R"(
+            partition_at_keys {
+                split_points {
+                    type { tuple_type { elements { optional_type { item { type_id: UINT64 } } } } }
+                    value { items { uint64_value: 10 } }
+                }
+                split_points {
+                    type { tuple_type { elements { optional_type { item { type_id: UINT64 } } } } }
+                    value { items { uint64_value: 20 } }
+                }
+                split_points {
+                    type { tuple_type { elements { optional_type { item { type_id: UINT64 } } } } }
+                    value { items { uint64_value: 30 } }
+                }
+            }
+        )", &settings));
+
+        TBlockEvents<TEvSchemeShard::TEvModifySchemeTransaction> indexApplicationBlocker(runtime, [](const auto& ev) {
+            const auto& modifyScheme = ev->Get()->Record.GetTransaction(0);
+            return modifyScheme.GetOperationType() == NKikimrSchemeOp::ESchemeOpApplyIndexBuild;
+        });
+
+        ui64 indexInitializationTx = 0;
+        TWaitForFirstEvent<TEvSchemeShard::TEvModifySchemeTransaction> indexInitializationWaiter(runtime,
+            [&indexInitializationTx](const auto& ev){
+                const auto& record = ev->Get()->Record;
+                if (record.GetTransaction(0).GetOperationType() == NKikimrSchemeOp::ESchemeOpCreateIndexBuild) {
+                    indexInitializationTx = record.GetTxId();
+                    return true;
+                }
+                return false;
+            }
+        );
+
+        const ui64 buildIndexTx = ++txId;
+        TestBuildIndex(runtime,  buildIndexTx, TTestTxConfig::SchemeShard, "/MyRoot", "/MyRoot/Table", TBuildIndexConfig{
+            "ByValue", NKikimrSchemeOp::EIndexTypeGlobal, { "value" }, {},
+            { NYdb::NTable::TGlobalIndexSettings::FromProto(settings) }
+        });
+
+        indexInitializationWaiter.Wait();
+        UNIT_ASSERT_VALUES_UNEQUAL(indexInitializationTx, 0);
+        env.TestWaitNotification(runtime, indexInitializationTx);
+
+        TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue"), {
+            NLs::PathExist,
+            NLs::IndexState(NKikimrSchemeOp::EIndexStateWriteOnly)
+        });
+
+        TVector<ui64> indexShards;
+        auto shardCollector = [&indexShards](const NKikimrScheme::TEvDescribeSchemeResult& record) {
+            UNIT_ASSERT_VALUES_EQUAL(record.GetStatus(), NKikimrScheme::StatusSuccess);
+            const auto& partitions = record.GetPathDescription().GetTablePartitions();
+            indexShards.clear();
+            indexShards.reserve(partitions.size());
+            for (const auto& partition : partitions) {
+                indexShards.emplace_back(partition.GetDatashardId());
+            }
+        };
+        TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue/indexImplTable", true), {
+            NLs::PathExist,
+            NLs::PartitionCount(4),
+            shardCollector
+        });
+        UNIT_ASSERT_VALUES_EQUAL(indexShards.size(), 4);
+
+        {
+            // make sure no shards are merged
+            TBlockEvents<TEvSchemeShard::TEvModifySchemeTransaction> mergeBlocker(runtime, [](const auto& ev) {
+                const auto& modifyScheme = ev->Get()->Record.GetTransaction(0);
+                return modifyScheme.GetOperationType() == NKikimrSchemeOp::ESchemeOpSplitMergeTablePartitions;
+            });
+
+            {
+                // wait for all index shards to send statistics
+                THashSet<ui64> shardsWithStats;
+                using TEvType = TEvDataShard::TEvPeriodicTableStats;
+                auto statsObserver = runtime.AddObserver<TEvType>([&shardsWithStats](const TEvType::TPtr& ev) {
+                    shardsWithStats.emplace(ev->Get()->Record.GetDatashardId());
+                });
+
+                runtime.WaitFor("all index shards to send statistics", [&]{
+                    return AllOf(indexShards, [&shardsWithStats](ui64 indexShard) {
+                        return shardsWithStats.contains(indexShard);
+                    });
+                });
+            }
+
+            // we expect to not have observed any attempts to merge
+            UNIT_ASSERT(mergeBlocker.empty());
+
+            // wait for 1 minute to ensure that no merges have been started by SchemeShard
+            env.SimulateSleep(runtime, TDuration::Minutes(1));
+            UNIT_ASSERT(mergeBlocker.empty());
+        }
+
+        // splits are allowed even if the index is not ready
+        TestSplitTable(runtime, ++txId, "/MyRoot/Table/ByValue/indexImplTable", Sprintf(R"(
+                    SourceTabletId: %lu
+                    SplitBoundary { KeyPrefix { Tuple { Optional { Uint64: 5 } } } }
+                )",
+                indexShards.front()
+            )
+        );
+        env.TestWaitNotification(runtime, txId);
+
+        indexApplicationBlocker.Stop().Unblock();
+        env.TestWaitNotification(runtime, buildIndexTx);
+
+        TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue"), {
+            NLs::IndexState(NKikimrSchemeOp::EIndexStateReady)
+        });
+
+        // wait until all index impl table shards are merged into one
+        while (true) {
+            TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue/indexImplTable", true), {
+                shardCollector
+            });
+            if (indexShards.size() > 1) {
+                // If a merge happens, old shards are deleted and replaced with a new one.
+                // That is why we need to wait for * all * the shards to be deleted.
+                env.TestWaitTabletDeletion(runtime, indexShards);
+            } else {
+                break;
+            }
+        }
+    }
+
     Y_UNIT_TEST(DropIndex) {
         TTestBasicRuntime runtime;
         TTestEnv env(runtime);
diff --git a/ydb/core/tx/schemeshard/ut_split_merge/ut_split_merge.cpp b/ydb/core/tx/schemeshard/ut_split_merge/ut_split_merge.cpp
index 2ea65bb9caea..947da178f4b4 100644
--- a/ydb/core/tx/schemeshard/ut_split_merge/ut_split_merge.cpp
+++ b/ydb/core/tx/schemeshard/ut_split_merge/ut_split_merge.cpp
@@ -1,4 +1,5 @@
 #include <ydb/core/tablet_flat/util_fmt_cell.h>
+#include <ydb/core/testlib/actors/block_events.h>
 #include <ydb/core/tx/schemeshard/ut_helpers/helpers.h>
 #include <ydb/core/tx/schemeshard/schemeshard_utils.h>
 
@@ -277,6 +278,69 @@ Y_UNIT_TEST_SUITE(TSchemeShardSplitBySizeTest) {
         // test requires more txids than cached at start
     }
 
+    Y_UNIT_TEST(MergeIndexTableShards) {
+        TTestBasicRuntime runtime;
+
+        TTestEnvOptions opts;
+        opts.EnableBackgroundCompaction(false);
+        TTestEnv env(runtime, opts);
+
+        ui64 txId = 100;
+
+        TBlockEvents<TEvDataShard::TEvPeriodicTableStats> statsBlocker(runtime);
+
+        TestCreateIndexedTable(runtime, ++txId, "/MyRoot", R"(
+                TableDescription {
+                    Name: "Table"
+                    Columns { Name: "key" Type: "Uint64" }
+                    Columns { Name: "value" Type: "Utf8" }
+                    KeyColumnNames: ["key"]
+                }
+                IndexDescription {
+                    Name: "ByValue"
+                    KeyColumnNames: ["value"]
+                    IndexImplTableDescriptions {
+                        SplitBoundary { KeyPrefix { Tuple { Optional { Text: "A" } } } }
+                        SplitBoundary { KeyPrefix { Tuple { Optional { Text: "B" } } } }
+                        SplitBoundary { KeyPrefix { Tuple { Optional { Text: "C" } } } }
+                    }
+                }
+            )"
+        );
+        env.TestWaitNotification(runtime, txId);
+
+        TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue/indexImplTable", true),
+            { NLs::PartitionCount(4) }
+        );
+
+        statsBlocker.Stop().Unblock();
+
+        TVector<ui64> indexShards;
+        auto shardCollector = [&indexShards](const NKikimrScheme::TEvDescribeSchemeResult& record) {
+            UNIT_ASSERT_VALUES_EQUAL(record.GetStatus(), NKikimrScheme::StatusSuccess);
+            const auto& partitions = record.GetPathDescription().GetTablePartitions();
+            indexShards.clear();
+            indexShards.reserve(partitions.size());
+            for (const auto& partition : partitions) {
+                indexShards.emplace_back(partition.GetDatashardId());
+            }
+        };
+
+        // wait until all index impl table shards are merged into one
+        while (true) {
+            TestDescribeResult(DescribePrivatePath(runtime, "/MyRoot/Table/ByValue/indexImplTable", true), {
+                shardCollector
+            });
+            if (indexShards.size() > 1) {
+                // If a merge happens, old shards are deleted and replaced with a new one.
+                // That is why we need to wait for * all * the shards to be deleted.
+                env.TestWaitTabletDeletion(runtime, indexShards);
+            } else {
+                break;
+            }
+        }
+    }
+
     Y_UNIT_TEST(AutoMergeInOne) {
         TTestWithReboots t;
         t.Run([&](TTestActorRuntime& runtime, bool& activeZone) {