diff --git a/app/code/Magento/CatalogInventory/Observer/AddStockItemsObserver.php b/app/code/Magento/CatalogInventory/Observer/AddStockItemsObserver.php
new file mode 100644
index 0000000000000..8fa90cf6531c4
--- /dev/null
+++ b/app/code/Magento/CatalogInventory/Observer/AddStockItemsObserver.php
@@ -0,0 +1,77 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\CatalogInventory\Observer;
+
+use Magento\Catalog\Model\Product;
+use Magento\Catalog\Model\ResourceModel\Product\Collection;
+use Magento\CatalogInventory\Api\StockConfigurationInterface;
+use Magento\CatalogInventory\Api\StockItemCriteriaInterfaceFactory;
+use Magento\CatalogInventory\Api\StockItemRepositoryInterface;
+use Magento\Framework\Event\Observer;
+use Magento\Framework\Event\ObserverInterface;
+
+/**
+ * Add Stock items to product collection.
+ */
+class AddStockItemsObserver implements ObserverInterface
+{
+    /**
+     * @var StockItemCriteriaInterfaceFactory
+     */
+    private $criteriaInterfaceFactory;
+
+    /**
+     * @var StockItemRepositoryInterface
+     */
+    private $stockItemRepository;
+
+    /**
+     * @var StockConfigurationInterface
+     */
+    private $stockConfiguration;
+
+    /**
+     * AddStockItemsObserver constructor.
+     *
+     * @param StockItemCriteriaInterfaceFactory $criteriaInterfaceFactory
+     * @param StockItemRepositoryInterface $stockItemRepository
+     * @param StockConfigurationInterface $stockConfiguration
+     */
+    public function __construct(
+        StockItemCriteriaInterfaceFactory $criteriaInterfaceFactory,
+        StockItemRepositoryInterface $stockItemRepository,
+        StockConfigurationInterface $stockConfiguration
+    ) {
+        $this->criteriaInterfaceFactory = $criteriaInterfaceFactory;
+        $this->stockItemRepository = $stockItemRepository;
+        $this->stockConfiguration = $stockConfiguration;
+    }
+
+    /**
+     * Add stock items to products in collection.
+     *
+     * @param Observer $observer
+     * @return void
+     */
+    public function execute(Observer $observer)
+    {
+        /** @var Collection $productCollection */
+        $productCollection = $observer->getData('collection');
+        $productIds = array_keys($productCollection->getItems());
+        $criteria = $this->criteriaInterfaceFactory->create();
+        $criteria->setProductsFilter($productIds);
+        $criteria->setScopeFilter($this->stockConfiguration->getDefaultScopeId());
+        $stockItemCollection = $this->stockItemRepository->getList($criteria);
+        foreach ($stockItemCollection->getItems() as $item) {
+            /** @var Product $product */
+            $product = $productCollection->getItemById($item->getProductId());
+            $productExtension = $product->getExtensionAttributes();
+            $productExtension->setStockItem($item);
+            $product->setExtensionAttributes($productExtension);
+        }
+    }
+}
diff --git a/app/code/Magento/CatalogInventory/Test/Unit/Observer/AddStockItemsObserverTest.php b/app/code/Magento/CatalogInventory/Test/Unit/Observer/AddStockItemsObserverTest.php
new file mode 100644
index 0000000000000..8de05bd014039
--- /dev/null
+++ b/app/code/Magento/CatalogInventory/Test/Unit/Observer/AddStockItemsObserverTest.php
@@ -0,0 +1,165 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\CatalogInventory\Test\Unit\Observer;
+
+use Magento\Catalog\Api\Data\ProductExtensionInterface;
+use Magento\Catalog\Model\Product;
+use Magento\Catalog\Model\ResourceModel\Product\Collection as ProductCollection;
+use Magento\CatalogInventory\Api\Data\StockItemCollectionInterface;
+use Magento\CatalogInventory\Api\Data\StockItemInterface;
+use Magento\CatalogInventory\Api\StockConfigurationInterface;
+use Magento\CatalogInventory\Api\StockItemCriteriaInterface;
+use Magento\CatalogInventory\Api\StockItemCriteriaInterfaceFactory;
+use Magento\CatalogInventory\Api\StockItemRepositoryInterface;
+use Magento\CatalogInventory\Observer\AddStockItemsObserver;
+use Magento\Framework\Event\Observer;
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager;
+use PHPUnit\Framework\TestCase;
+
+class AddStockItemsObserverTest extends TestCase
+{
+    /**
+     * Test subject.
+     *
+     * @var AddStockItemsObserver
+     */
+    private $subject;
+    /**
+     * @var StockItemCriteriaInterfaceFactory|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $criteriaInterfaceFactoryMock;
+
+    /**
+     * @var StockItemRepositoryInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $stockItemRepositoryMock;
+
+    /**
+     * @var StockConfigurationInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $stockConfigurationMock;
+
+    /**
+     * @inheritdoc
+     */
+    protected function setUp()
+    {
+        $objectManager = new ObjectManager($this);
+        $this->criteriaInterfaceFactoryMock = $this->getMockBuilder(StockItemCriteriaInterfaceFactory::class)
+            ->setMethods(['create'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $this->stockItemRepositoryMock = $this->getMockBuilder(StockItemRepositoryInterface::class)
+            ->setMethods(['getList'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $this->stockConfigurationMock = $this->getMockBuilder(StockConfigurationInterface::class)
+            ->setMethods(['getDefaultScopeId'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $this->subject = $objectManager->getObject(
+            AddStockItemsObserver::class,
+            [
+                'criteriaInterfaceFactory' => $this->criteriaInterfaceFactoryMock,
+                'stockItemRepository' => $this->stockItemRepositoryMock,
+                'stockConfiguration' => $this->stockConfigurationMock
+            ]
+        );
+    }
+
+    /**
+     * Test AddStockItemsObserver::execute() add stock item to product as extension attribute.
+     */
+    public function testExecute()
+    {
+        $productId = 1;
+        $defaultScopeId = 0;
+
+        $criteria = $this->getMockBuilder(StockItemCriteriaInterface::class)
+            ->setMethods(['setProductsFilter', 'setScopeFilter'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $criteria->expects(self::once())
+            ->method('setProductsFilter')
+            ->with(self::identicalTo([$productId]))
+            ->willReturn(true);
+        $criteria->expects(self::once())
+            ->method('setScopeFilter')
+            ->with(self::identicalTo($defaultScopeId))
+            ->willReturn(true);
+
+        $this->criteriaInterfaceFactoryMock->expects(self::once())
+            ->method('create')
+            ->willReturn($criteria);
+        $stockItemCollection = $this->getMockBuilder(StockItemCollectionInterface::class)
+            ->setMethods(['getItems'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $stockItem = $this->getMockBuilder(StockItemInterface::class)
+            ->setMethods(['getProductId'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $stockItem->expects(self::once())
+            ->method('getProductId')
+            ->willReturn($productId);
+
+        $stockItemCollection->expects(self::once())
+            ->method('getItems')
+            ->willReturn([$stockItem]);
+
+        $this->stockItemRepositoryMock->expects(self::once())
+            ->method('getList')
+            ->with(self::identicalTo($criteria))
+            ->willReturn($stockItemCollection);
+
+        $this->stockConfigurationMock->expects(self::once())
+            ->method('getDefaultScopeId')
+            ->willReturn($defaultScopeId);
+
+        $productExtension = $this->getMockBuilder(ProductExtensionInterface::class)
+            ->setMethods(['setStockItem'])
+            ->disableOriginalConstructor()
+            ->getMockForAbstractClass();
+        $productExtension->expects(self::once())
+            ->method('setStockItem')
+            ->with(self::identicalTo($stockItem));
+
+        $product = $this->getMockBuilder(Product::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $product->expects(self::once())
+            ->method('getExtensionAttributes')
+            ->willReturn($productExtension);
+        $product->expects(self::once())
+            ->method('setExtensionAttributes')
+            ->with(self::identicalTo($productExtension))
+            ->willReturnSelf();
+
+        /** @var ProductCollection|\PHPUnit_Framework_MockObject_MockObject $productCollection */
+        $productCollection = $this->getMockBuilder(ProductCollection::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $productCollection->expects(self::once())
+            ->method('getItems')
+            ->willReturn([$productId => $product]);
+        $productCollection->expects(self::once())
+            ->method('getItemById')
+            ->with(self::identicalTo($productId))
+            ->willReturn($product);
+
+        /** @var Observer|\PHPUnit_Framework_MockObject_MockObject $observer */
+        $observer = $this->getMockBuilder(Observer::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $observer->expects(self::once())
+            ->method('getData')
+            ->with('collection')
+            ->willReturn($productCollection);
+
+        $this->subject->execute($observer);
+    }
+}
diff --git a/app/code/Magento/CatalogInventory/etc/events.xml b/app/code/Magento/CatalogInventory/etc/events.xml
index 3b5f2483ec57e..0a9f3c2d40dca 100644
--- a/app/code/Magento/CatalogInventory/etc/events.xml
+++ b/app/code/Magento/CatalogInventory/etc/events.xml
@@ -42,4 +42,7 @@
     <event name="admin_system_config_changed_section_cataloginventory">
         <observer name="inventory" instance="Magento\CatalogInventory\Observer\UpdateItemsStockUponConfigChangeObserver"/>
     </event>
+    <event name="sales_quote_item_collection_products_after_load">
+        <observer name="add_stock_items" instance="Magento\CatalogInventory\Observer\AddStockItemsObserver"/>
+    </event>
 </config>
diff --git a/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty.php b/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty.php
new file mode 100644
index 0000000000000..37ce93cc9c420
--- /dev/null
+++ b/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty.php
@@ -0,0 +1,192 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+use Magento\Catalog\Api\Data\ProductTierPriceExtensionFactory;
+
+\Magento\TestFramework\Helper\Bootstrap::getInstance()->reinitialize();
+
+/** @var \Magento\TestFramework\ObjectManager $objectManager */
+$objectManager = \Magento\TestFramework\Helper\Bootstrap::getObjectManager();
+
+/** @var \Magento\Catalog\Api\CategoryLinkManagementInterface $categoryLinkManagement */
+$categoryLinkManagement = $objectManager->get(\Magento\Catalog\Api\CategoryLinkManagementInterface::class);
+
+$tierPrices = [];
+/** @var \Magento\Catalog\Api\Data\ProductTierPriceInterfaceFactory $tierPriceFactory */
+$tierPriceFactory = $objectManager->get(\Magento\Catalog\Api\Data\ProductTierPriceInterfaceFactory::class);
+/** @var  $tpExtensionAttributes */
+$tpExtensionAttributesFactory = $objectManager->get(ProductTierPriceExtensionFactory::class);
+
+$adminWebsite = $objectManager->get(\Magento\Store\Api\WebsiteRepositoryInterface::class)->get('admin');
+$tierPriceExtensionAttributes1 = $tpExtensionAttributesFactory->create()
+    ->setWebsiteId($adminWebsite->getId());
+
+$tierPrices[] = $tierPriceFactory->create(
+    [
+        'data' => [
+            'customer_group_id' => \Magento\Customer\Model\Group::CUST_GROUP_ALL,
+            'qty' => 2,
+            'value' => 8,
+        ],
+    ]
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
+
+$tierPrices[] = $tierPriceFactory->create(
+    [
+        'data' => [
+            'customer_group_id' => \Magento\Customer\Model\Group::CUST_GROUP_ALL,
+            'qty' => 5,
+            'value' => 5,
+        ],
+    ]
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
+
+$tierPrices[] = $tierPriceFactory->create(
+    [
+        'data' => [
+            'customer_group_id' => \Magento\Customer\Model\Group::NOT_LOGGED_IN_ID,
+            'qty' => 3,
+            'value' => 5,
+        ],
+    ]
+)->setExtensionAttributes($tierPriceExtensionAttributes1);
+
+$tierPriceExtensionAttributes2 = $tpExtensionAttributesFactory->create()
+    ->setWebsiteId($adminWebsite->getId())
+    ->setPercentageValue(50);
+
+$tierPrices[] = $tierPriceFactory->create(
+    [
+        'data' => [
+            'customer_group_id' => \Magento\Customer\Model\Group::NOT_LOGGED_IN_ID,
+            'qty' => 10,
+        ],
+    ]
+)->setExtensionAttributes($tierPriceExtensionAttributes2);
+
+/** @var $product \Magento\Catalog\Model\Product */
+$product = $objectManager->create(\Magento\Catalog\Model\Product::class);
+$product->isObjectNew(true);
+$product->setTypeId(\Magento\Catalog\Model\Product\Type::TYPE_SIMPLE)
+    ->setId(1)
+    ->setAttributeSetId(4)
+    ->setWebsiteIds([1])
+    ->setName('Simple Product')
+    ->setSku('simple_with_decimal_qty')
+    ->setPrice(10)
+    ->setWeight(1)
+    ->setShortDescription("Short description")
+    ->setTaxClassId(0)
+    ->setTierPrices($tierPrices)
+    ->setDescription('Description with <b>html tag</b>')
+    ->setMetaTitle('meta title')
+    ->setMetaKeyword('meta keyword')
+    ->setMetaDescription('meta description')
+    ->setVisibility(\Magento\Catalog\Model\Product\Visibility::VISIBILITY_BOTH)
+    ->setStatus(\Magento\Catalog\Model\Product\Attribute\Source\Status::STATUS_ENABLED)
+    ->setStockData(
+        [
+            'use_config_manage_stock' => 1,
+            'qty' => 100,
+            'is_qty_decimal' => 1,
+            'is_in_stock' => 1,
+        ]
+    )->setCanSaveCustomOptions(true)
+    ->setHasOptions(true);
+
+$oldOptions = [
+    [
+        'previous_group' => 'text',
+        'title' => 'Test Field',
+        'type' => 'field',
+        'is_require' => 1,
+        'sort_order' => 0,
+        'price' => 1,
+        'price_type' => 'fixed',
+        'sku' => '1-text',
+        'max_characters' => 100,
+    ],
+    [
+        'previous_group' => 'date',
+        'title' => 'Test Date and Time',
+        'type' => 'date_time',
+        'is_require' => 1,
+        'sort_order' => 0,
+        'price' => 2,
+        'price_type' => 'fixed',
+        'sku' => '2-date',
+    ],
+    [
+        'previous_group' => 'select',
+        'title' => 'Test Select',
+        'type' => 'drop_down',
+        'is_require' => 1,
+        'sort_order' => 0,
+        'values' => [
+            [
+                'option_type_id' => null,
+                'title' => 'Option 1',
+                'price' => 3,
+                'price_type' => 'fixed',
+                'sku' => '3-1-select',
+            ],
+            [
+                'option_type_id' => null,
+                'title' => 'Option 2',
+                'price' => 3,
+                'price_type' => 'fixed',
+                'sku' => '3-2-select',
+            ],
+        ],
+    ],
+    [
+        'previous_group' => 'select',
+        'title' => 'Test Radio',
+        'type' => 'radio',
+        'is_require' => 1,
+        'sort_order' => 0,
+        'values' => [
+            [
+                'option_type_id' => null,
+                'title' => 'Option 1',
+                'price' => 3,
+                'price_type' => 'fixed',
+                'sku' => '4-1-radio',
+            ],
+            [
+                'option_type_id' => null,
+                'title' => 'Option 2',
+                'price' => 3,
+                'price_type' => 'fixed',
+                'sku' => '4-2-radio',
+            ],
+        ],
+    ],
+];
+
+$options = [];
+
+/** @var \Magento\Catalog\Api\Data\ProductCustomOptionInterfaceFactory $customOptionFactory */
+$customOptionFactory = $objectManager->create(\Magento\Catalog\Api\Data\ProductCustomOptionInterfaceFactory::class);
+
+foreach ($oldOptions as $option) {
+    /** @var \Magento\Catalog\Api\Data\ProductCustomOptionInterface $option */
+    $option = $customOptionFactory->create(['data' => $option]);
+    $option->setProductSku($product->getSku());
+
+    $options[] = $option;
+}
+
+$product->setOptions($options);
+
+/** @var \Magento\Catalog\Api\ProductRepositoryInterface $productRepositoryFactory */
+$productRepository = $objectManager->create(\Magento\Catalog\Api\ProductRepositoryInterface::class);
+$productRepository->save($product);
+
+$categoryLinkManagement->assignProductToCategories(
+    $product->getSku(),
+    [2]
+);
diff --git a/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty_rollback.php b/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty_rollback.php
new file mode 100644
index 0000000000000..55bd53a2d5794
--- /dev/null
+++ b/dev/tests/integration/testsuite/Magento/Catalog/_files/product_simple_with_decimal_qty_rollback.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+use Magento\Framework\Exception\NoSuchEntityException;
+
+\Magento\TestFramework\Helper\Bootstrap::getInstance()->getInstance()->reinitialize();
+
+/** @var \Magento\Framework\Registry $registry */
+$registry = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()->get(\Magento\Framework\Registry::class);
+
+$registry->unregister('isSecureArea');
+$registry->register('isSecureArea', true);
+
+/** @var \Magento\Catalog\Api\ProductRepositoryInterface $productRepository */
+$productRepository = \Magento\TestFramework\Helper\Bootstrap::getObjectManager()
+    ->get(\Magento\Catalog\Api\ProductRepositoryInterface::class);
+try {
+    $product = $productRepository->get('simple_with_decimal_qty', false, null, true);
+    $productRepository->delete($product);
+} catch (NoSuchEntityException $e) {
+}
+$registry->unregister('isSecureArea');
+$registry->register('isSecureArea', false);
diff --git a/dev/tests/integration/testsuite/Magento/CatalogInventory/Observer/AddStockItemsObserverTest.php b/dev/tests/integration/testsuite/Magento/CatalogInventory/Observer/AddStockItemsObserverTest.php
new file mode 100644
index 0000000000000..71af5d102a8d7
--- /dev/null
+++ b/dev/tests/integration/testsuite/Magento/CatalogInventory/Observer/AddStockItemsObserverTest.php
@@ -0,0 +1,41 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\CatalogInventory\Observer;
+
+use Magento\CatalogInventory\Api\Data\StockItemInterface;
+use Magento\Quote\Model\Quote;
+use Magento\Quote\Model\ResourceModel\Quote\Item\Collection;
+use Magento\Quote\Model\ResourceModel\Quote\Item\CollectionFactory;
+use Magento\TestFramework\Helper\Bootstrap;
+use PHPUnit\Framework\TestCase;
+
+class AddStockItemsObserverTest extends TestCase
+{
+    /**
+     * Test addStockItemsObserver add stock items to products as extension attributes in quote item collection.
+     *
+     * @magentoDataFixture Magento/Sales/_files/quote.php
+     */
+    public function testAddStockItemsToProductCollection()
+    {
+        $quote = Bootstrap::getObjectManager()->create(Quote::class);
+        $quote->load('test01', 'reserved_order_id');
+        /** @var CollectionFactory $collectionFactory */
+        $collectionFactory = Bootstrap::getObjectManager()->create(CollectionFactory::class);
+        /** @var Collection $collection */
+        $collection = $collectionFactory->create();
+        $collection->setQuote($quote);
+        /** @var Quote\Item $quoteItem */
+        foreach ($collection->getItems() as $quoteItem) {
+            self::assertNotEmpty($quoteItem->getProduct()->getExtensionAttributes()->getStockItem());
+            self::assertInstanceOf(
+                StockItemInterface::class,
+                $quoteItem->getProduct()->getExtensionAttributes()->getStockItem()
+            );
+        }
+    }
+}
diff --git a/dev/tests/integration/testsuite/Magento/Sales/Model/AdminOrder/CreateTest.php b/dev/tests/integration/testsuite/Magento/Sales/Model/AdminOrder/CreateTest.php
index a4dac0f285f58..28b2575643b05 100644
--- a/dev/tests/integration/testsuite/Magento/Sales/Model/AdminOrder/CreateTest.php
+++ b/dev/tests/integration/testsuite/Magento/Sales/Model/AdminOrder/CreateTest.php
@@ -390,7 +390,7 @@ public function testCreateOrderNewCustomerDifferentAddresses()
     }
 
     /**
-     * @magentoDataFixture Magento/Catalog/_files/product_simple.php
+     * @magentoDataFixture Magento/Catalog/_files/product_simple_with_decimal_qty.php
      * @magentoDbIsolation enabled
      * @magentoAppIsolation enabled
      */
@@ -421,6 +421,10 @@ public function testCreateOrderNewCustomer()
             $paymentMethod
         );
         $order = $this->_model->createOrder();
+        //Check, order considering decimal qty in product.
+        foreach ($order->getItems() as $orderItem) {
+            self::assertTrue($orderItem->getIsQtyDecimal());
+        }
         $this->_verifyCreatedOrder($order, $shippingMethod);
     }