diff --git a/app/code/Magento/InventoryApi/Test/_files/products.php b/app/code/Magento/InventoryApi/Test/_files/products.php
index 4c04fdd9c642..08ce6888fd95 100644
--- a/app/code/Magento/InventoryApi/Test/_files/products.php
+++ b/app/code/Magento/InventoryApi/Test/_files/products.php
@@ -16,6 +16,24 @@
 $productRepository = $objectManager->get(ProductRepositoryInterface::class);
 $productRepository->cleanCache();
 
+$stockData = [
+    'SKU-1' => [
+        'qty' => 8.5,
+        'is_in_stock' => true,
+        'manage_stock' => true
+    ],
+    'SKU-2' => [
+        'qty' => 5,
+        'is_in_stock' => true,
+        'manage_stock' => true
+    ],
+    'SKU-3' => [
+        'qty' => 0,
+        'is_in_stock' => false,
+        'manage_stock' => true
+    ]
+];
+
 for ($i = 1; $i <= 3; $i++) {
     $product = $productFactory->create();
     $product->setTypeId(Type::TYPE_SIMPLE)
@@ -23,6 +41,7 @@
         ->setName('Simple Product ' . $i)
         ->setSku('SKU-' . $i)
         ->setPrice(10)
+        ->setStockData($stockData['SKU-' . $i])
         ->setStatus(Status::STATUS_ENABLED);
     $productRepository->save($product);
 }
diff --git a/app/code/Magento/InventoryApi/Test/_files/products_rollback.php b/app/code/Magento/InventoryApi/Test/_files/products_rollback.php
index 021e40448a00..06de7fe3b82c 100644
--- a/app/code/Magento/InventoryApi/Test/_files/products_rollback.php
+++ b/app/code/Magento/InventoryApi/Test/_files/products_rollback.php
@@ -4,6 +4,8 @@
  * See COPYING.txt for license details.
  */
 use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\CatalogInventory\Api\StockStatusCriteriaInterfaceFactory;
+use Magento\CatalogInventory\Api\StockStatusRepositoryInterface;
 use Magento\Framework\Registry;
 use Magento\TestFramework\Helper\Bootstrap;
 
@@ -12,12 +14,25 @@
 $productRepository = $objectManager->create(ProductRepositoryInterface::class);
 /** @var Registry $registry */
 $registry = $objectManager->get(Registry::class);
+/** @var StockStatusRepositoryInterface $stockStatusRepository */
+$stockStatusRepository = $objectManager->create(StockStatusRepositoryInterface::class);
+/** @var StockStatusCriteriaInterfaceFactory $stockStatusCriteriaFactory */
+$stockStatusCriteriaFactory = $objectManager->create(StockStatusCriteriaInterfaceFactory::class);
 
 $currentArea = $registry->registry('isSecureArea');
 $registry->unregister('isSecureArea');
 $registry->register('isSecureArea', true);
 
 for ($i = 1; $i <= 3; $i++) {
+    $product = $productRepository->get('SKU-' . $i);
+    /** @var \Magento\CatalogInventory\Api\StockStatusCriteriaInterfaceFactory $stockStatusCriteriaFactory **/
+    $criteria = $stockStatusCriteriaFactory->create();
+    $criteria->setProductsFilter($product->getId());
+
+    $result = $stockStatusRepository->getList($criteria);
+    $stockStatus = current($result->getItems());
+    $stockStatusRepository->delete($stockStatus);
+
     $productRepository->deleteById('SKU-' . $i);
 }
 
diff --git a/app/code/Magento/InventoryCatalog/Plugin/Model/UpdateLegacyCatalogInventoryPlugin.php b/app/code/Magento/InventoryCatalog/Plugin/Model/UpdateLegacyCatalogInventoryPlugin.php
new file mode 100644
index 000000000000..ba6de0ccac19
--- /dev/null
+++ b/app/code/Magento/InventoryCatalog/Plugin/Model/UpdateLegacyCatalogInventoryPlugin.php
@@ -0,0 +1,88 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\InventoryCatalog\Plugin\Model;
+
+use Magento\Framework\App\ResourceConnection;
+use Magento\InventoryApi\Api\Data\ReservationInterface;
+use Magento\InventoryApi\Api\ReservationsAppendInterface;
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\CatalogInventory\Api\StockRegistryInterface;
+
+/**
+ * Plugin help to fill the legacy catalog inventory tables cataloginventory_stock_status and
+ * cataloginventory_stock_item to don't break the backward compatible.
+ */
+class UpdateLegacyCatalogInventoryPlugin
+{
+
+    /**
+     * @var ResourceConnection
+     */
+    private $resourceConnection;
+
+    /**
+     * @var ProductRepositoryInterface
+     */
+    private $productRepository;
+
+    /**
+     * @var \Magento\CatalogInventory\Api\StockRegistryInterface
+     */
+    private $stockRegistry;
+
+    /**
+     * @param ResourceConnection $resourceConnection
+     * @param ProductRepositoryInterface $productRepository
+     * @param StockRegistryInterface $stockRegistry
+     */
+    public function __construct(
+        ResourceConnection $resourceConnection,
+        ProductRepositoryInterface $productRepository,
+        StockRegistryInterface $stockRegistry
+    ) {
+        $this->resourceConnection = $resourceConnection;
+        $this->productRepository = $productRepository;
+        $this->stockRegistry = $stockRegistry;
+    }
+
+    /**
+     * Plugin method to fill the legacy tables.
+     *
+     * @param ReservationsAppendInterface $subject
+     * @param void $result
+     * @param ReservationInterface[] $reservations
+     *
+     * @see ReservationsAppendInterface::execute
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     * @return void
+     */
+    public function afterExecute(ReservationsAppendInterface $subject, $result, array $reservations)
+    {
+        $this->updateStockItemAndStatusTable($reservations);
+        return $result;
+    }
+
+    /**
+     * Updates cataloginventory_stock_item and cataloginventory_stock_status qty with reservation information.
+     *
+     * @param ReservationInterface[] $reservations
+     * @return void
+     */
+    private function updateStockItemAndStatusTable(array $reservations)
+    {
+        foreach ($reservations as $reservation) {
+            $sku = $reservation->getSku();
+            $stockItem = $this->stockRegistry->getStockItemBySku($sku);
+            $stockItem->setQty($stockItem->getQty() + $reservation->getQuantity());
+            $this->stockRegistry->updateStockItemBySku($sku, $stockItem);
+
+            $stockStatus = $this->stockRegistry->getStockStatus($stockItem->getProductId());
+            $stockStatus->setQty($stockStatus->getQty() + $reservation->getQuantity());
+            $stockStatus->save();
+        }
+    }
+}
diff --git a/app/code/Magento/InventoryCatalog/Test/Integration/UpdateLegacyCatalogInventoryPluginTest.php b/app/code/Magento/InventoryCatalog/Test/Integration/UpdateLegacyCatalogInventoryPluginTest.php
new file mode 100644
index 000000000000..d1be1262f809
--- /dev/null
+++ b/app/code/Magento/InventoryCatalog/Test/Integration/UpdateLegacyCatalogInventoryPluginTest.php
@@ -0,0 +1,152 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\InventoryCatalog\Test\Integration;
+
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Catalog\Model\Product;
+use Magento\InventoryApi\Api\ReservationBuilderInterface;
+use Magento\InventoryApi\Api\ReservationsAppendInterface;
+use PHPUnit\Framework\TestCase;
+use Magento\TestFramework\Helper\Bootstrap;
+use Magento\CatalogInventory\Api\StockItemRepositoryInterface;
+use Magento\CatalogInventory\Api\StockItemCriteriaInterface;
+use Magento\CatalogInventory\Api\StockItemCriteriaInterfaceFactory;
+use Magento\CatalogInventory\Api\Data\StockItemCollectionInterface;
+use Magento\CatalogInventory\Api\Data\StockItemInterface;
+use Magento\InventoryApi\Api\GetProductQuantityInStockInterface;
+use Magento\Indexer\Model\Indexer;
+use Magento\Inventory\Indexer\SourceItem\SourceItemIndexer;
+
+class UpdateLegacyCatalogInventoryPluginTest extends TestCase
+{
+    /**
+     * @var ReservationBuilderInterface
+     */
+    private $reservationBuilder;
+
+    /**
+     * @var ReservationsAppendInterface
+     */
+    private $reservationsAppend;
+
+    /**
+     * @var StockItemRepositoryInterface
+     */
+    private $oldStockItemRepository;
+
+    /**
+     * @var StockItemCriteriaInterfaceFactory
+     */
+    private $stockItemCriteriaFactory;
+
+    /**
+     * @var GetProductQuantityInStockInterface
+     */
+    private $getProductQtyInStock;
+
+    /**
+     * @var IndexerInterface
+     */
+    private $indexer;
+
+    /**
+     * @var ProductRepositoryInterface
+     */
+    private $productRepository;
+
+    protected function setUp()
+    {
+        $this->reservationBuilder = Bootstrap::getObjectManager()->get(ReservationBuilderInterface::class);
+        $this->reservationsAppend = Bootstrap::getObjectManager()->get(ReservationsAppendInterface::class);
+        $this->oldStockItemRepository = Bootstrap::getObjectManager()->get(StockItemRepositoryInterface::class);
+        $this->stockItemCriteriaFactory = Bootstrap::getObjectManager()->get(StockItemCriteriaInterfaceFactory::class);
+
+        $this->indexer = Bootstrap::getObjectManager()->get(Indexer::class);
+        $this->indexer->load(SourceItemIndexer::INDEXER_ID);
+        $this->getProductQtyInStock = Bootstrap::getObjectManager()->get(GetProductQuantityInStockInterface::class);
+        $this->productRepository = Bootstrap::getObjectManager()->get(ProductRepositoryInterface::class);
+    }
+
+    /**
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/products.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/sources.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/stocks.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/source_items.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/stock_source_link.php
+     */
+    public function testUpdateStockItemTable()
+    {
+        $reservationQuantity = -5;
+
+        /** @var Product $product */
+        $product = $this->productRepository->get('SKU-1');
+
+        /** @var StockItemCriteriaInterface  $criteria */
+        $criteria = $this->stockItemCriteriaFactory->create();
+        $criteria->setProductsFilter([$product->getId()]);
+
+        /** @var StockItemCollectionInterface $collectionBeforeChange */
+        $collectionBeforeChange = $this->oldStockItemRepository->getList($criteria);
+        /** @var StockItemInterface $oldStockItem */
+        $oldStockItem = current($collectionBeforeChange->getItems());
+        $initialQuantity = $oldStockItem->getQty();
+
+        $this->reservationsAppend->execute([
+            $this->reservationBuilder->setStockId(1)->setSku('SKU-1')->setQuantity($reservationQuantity)->build()
+        ]);
+
+        /** @var StockItemCollectionInterface $collectionAfterChange */
+        $collectionAfterChange = $this->oldStockItemRepository->getList($criteria);
+        $oldStockItem = current($collectionAfterChange->getItems());
+        $quantityAfterCheck = $oldStockItem->getQty();
+
+        $this->assertEquals($initialQuantity + $reservationQuantity, $quantityAfterCheck);
+    }
+
+    /**
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/products.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/sources.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/stocks.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/source_items.php
+     * @magentoDataFixture ../../../../app/code/Magento/InventoryApi/Test/_files/stock_source_link.php
+     */
+    public function testThatReservationPlacedUpdatesBothOldAndNewStocks()
+    {
+        $this->productRepository = Bootstrap::getObjectManager()->get(ProductRepositoryInterface::class);
+        $reservationQuantity = -5;
+
+        $this->indexer->reindexAll();
+        $this->assertEquals(8.5, $this->getProductQtyInStock->execute('SKU-1', 10));
+
+        /** @var Product $product */
+        $product = $this->productRepository->get('SKU-1');
+
+        /** @var StockItemCriteriaInterface  $criteria */
+        $criteria = $this->stockItemCriteriaFactory->create();
+        $criteria->setProductsFilter([$product->getId()]);
+
+        /** @var StockItemCollectionInterface $collectionBeforeChange */
+        $collectionBeforeChange = $this->oldStockItemRepository->getList($criteria);
+
+        /** @var StockItemInterface $oldStockItem */
+        $oldStockItem = current($collectionBeforeChange->getItems());
+        $initialQuantity = $oldStockItem->getQty();
+        $this->assertEquals(8.5, $initialQuantity);
+
+        $this->reservationsAppend->execute([
+            $this->reservationBuilder->setStockId(10)->setSku('SKU-1')->setQuantity($reservationQuantity)->build()
+        ]);
+
+        /** @var StockItemCollectionInterface $collectionAfterChange */
+        $collectionAfterChange = $this->oldStockItemRepository->getList($criteria);
+        $oldStockItem = current($collectionAfterChange->getItems());
+        $quantityAfterCheck = $oldStockItem->getQty();
+
+        $this->assertEquals(8.5 - 5, $this->getProductQtyInStock->execute('SKU-1', 10));
+        $this->assertEquals($this->getProductQtyInStock->execute('SKU-1', 10), $quantityAfterCheck);
+    }
+}
diff --git a/app/code/Magento/InventoryCatalog/etc/di.xml b/app/code/Magento/InventoryCatalog/etc/di.xml
index d7e40373206c..d394c22bdea2 100644
--- a/app/code/Magento/InventoryCatalog/etc/di.xml
+++ b/app/code/Magento/InventoryCatalog/etc/di.xml
@@ -14,4 +14,7 @@
         <plugin name="prevent_assigned_to_sales_channels_stock_deleting"
                 type="Magento\InventoryCatalog\Plugin\InventoryApi\StockRepository\PreventDeleting\AssignedToSalesChannelsStockPlugin"/>
     </type>
+    <type name="Magento\InventoryApi\Api\ReservationsAppendInterface">
+        <plugin name="update_legacy_catalog_inventory_plugin" type="Magento\InventoryCatalog\Plugin\Model\UpdateLegacyCatalogInventoryPlugin"/>
+    </type>
 </config>