diff --git a/packages/devextreme/js/__internal/grids/grid_core/m_utils.ts b/packages/devextreme/js/__internal/grids/grid_core/m_utils.ts
index 319552134421..b75a5e9e6318 100644
--- a/packages/devextreme/js/__internal/grids/grid_core/m_utils.ts
+++ b/packages/devextreme/js/__internal/grids/grid_core/m_utils.ts
@@ -23,6 +23,8 @@ import type { ColumnPoint } from '@ts/grids/grid_core/m_types';
 
 import { isEqualSelectors, isSelectorEqualWithCallback } from './utils/index';
 
+const BASE_LOAD_PANEL_Z_INDEX = 1000;
+
 const DATAGRID_SELECTION_DISABLED_CLASS = 'dx-selection-disabled';
 const DATAGRID_GROUP_OPENED_CLASS = 'dx-datagrid-group-opened';
 const DATAGRID_GROUP_CLOSED_CLASS = 'dx-datagrid-group-closed';
@@ -230,6 +232,7 @@ export default {
         shading: false,
         message: loadPanelOptions.text,
         container: $container,
+        zIndex: BASE_LOAD_PANEL_Z_INDEX,
       }, loadPanelOptions);
 
       that._loadPanel = that._createComponent($('<div>').appendTo($container), LoadPanel, loadPanelOptions);
diff --git a/packages/devextreme/js/__internal/ui/overlay/m_overlay.ts b/packages/devextreme/js/__internal/ui/overlay/m_overlay.ts
index 20ccc22974ad..4d27789c984e 100644
--- a/packages/devextreme/js/__internal/ui/overlay/m_overlay.ts
+++ b/packages/devextreme/js/__internal/ui/overlay/m_overlay.ts
@@ -90,6 +90,8 @@ interface OverlayProperties extends Properties {
 
   restorePosition?: boolean;
 
+  zIndex?: number;
+
   _fixWrapperPosition?: boolean;
 
   _skipContentPositioning?: boolean;
@@ -722,24 +724,42 @@ class Overlay<
     this._toggleSubscriptions(visible);
   }
 
+  _handleZIndexOptionChanged(): void {
+    const { zIndex } = this.option();
+
+    this._zIndex = zIndex ?? zIndexPool.create(this._zIndexInitValue());
+
+    this._updateZIndexStackPosition(this._isVisible());
+  }
+
   _updateZIndexStackPosition(pushToStack: boolean): void {
     const overlayStack = this._overlayStack();
     // @ts-expect-error ts-error
     const index = overlayStack.indexOf(this);
+    const isInStack = index !== -1;
+    const { zIndex } = this.option();
 
-    if (pushToStack) {
-      if (index === -1) {
-        this._zIndex = zIndexPool.create(this._zIndexInitValue());
-        // @ts-expect-error ts-error
-        overlayStack.push(this);
+    if (!pushToStack) {
+      if (isInStack) {
+        overlayStack.splice(index, 1);
+        zIndexPool.remove(this._zIndex);
       }
 
-      this._$wrapper.css('zIndex', this._zIndex);
-      this._$content.css('zIndex', this._zIndex);
-    } else if (index !== -1) {
-      overlayStack.splice(index, 1);
-      zIndexPool.remove(this._zIndex);
+      return;
     }
+
+    if (!isInStack) {
+      this._zIndex = zIndex ?? zIndexPool.create(this._zIndexInitValue());
+      // @ts-expect-error this and Overlay have no overlap
+      overlayStack.push(this);
+    }
+
+    this._updateZIndex();
+  }
+
+  _updateZIndex(): void {
+    this._$wrapper.css('zIndex', this._zIndex);
+    this._$content.css('zIndex', this._zIndex);
   }
 
   _toggleShading(visible?: boolean): void {
@@ -1319,6 +1339,9 @@ class Overlay<
         this._initHideTopOverlayHandler(value);
         this._toggleHideTopOverlayCallback(this.option('visible'));
         break;
+      case 'zIndex':
+        this._handleZIndexOptionChanged();
+        break;
       case 'hideOnParentScroll':
       case '_hideOnParentScrollTarget': {
         const { visible } = this.option();
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets.dataGrid/dataGrid.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets.dataGrid/dataGrid.tests.js
index 91e9931ccd9d..f8c2ea15867e 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets.dataGrid/dataGrid.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets.dataGrid/dataGrid.tests.js
@@ -1275,6 +1275,21 @@ QUnit.module('Initialization', baseModuleConfig, () => {
         // assert
         assert.strictEqual(onContentReadySpy.callCount, 1, 'onContentReadySpy call count');
     });
+
+    QUnit.test('Load panel has custom z-index (T1308742)', function(assert) {
+        const dataGrid = createDataGrid({
+            dataSource: {
+                load: function() {
+                    return;
+                }
+            }
+        });
+
+        const loadPanel = dataGrid.getView('rowsView')._loadPanel;
+        const loadPanelZIndex = loadPanel._zIndex;
+
+        assert.strictEqual(loadPanelZIndex, 1000, 'load z-index is set to 1000 by default');
+    });
 });
 
 
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets/overlay.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets/overlay.tests.js
index 607f99620619..1c8404f8b9c4 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets/overlay.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets/overlay.tests.js
@@ -3108,6 +3108,50 @@ testModule('API', moduleConfig, () => {
         assert.strictEqual(resizeStub.callCount, 1, '\'dxresize\' event handler was called');
         resizeStub.restore();
     });
+
+    test('Overlay uses custom zIndex on init if zIndex option is provided', function(assert) {
+        const overlay = $('#overlay').dxOverlay({
+            visible: true,
+            zIndex: 2000
+        }).dxOverlay('instance');
+
+        const contentZIndex = Number(getComputedStyle(overlay.$content()[0]).zIndex);
+
+        assert.strictEqual(contentZIndex, 2000, 'custom zIndex assigned');
+    });
+
+    test('Changing zIndex option replaces old pool zIndex with custom', function(assert) {
+        const overlay = $('#overlay').dxOverlay({
+            visible: true
+        }).dxOverlay('instance');
+
+        const initialZIndex = Number(getComputedStyle(overlay.$content()[0]).zIndex);
+
+        assert.strictEqual(initialZIndex, 1501, 'overlay has initial pool zIndex');
+
+        overlay.option('zIndex', 5000);
+
+        const finalZIndex = Number(getComputedStyle(overlay.$content()[0]).zIndex);
+
+        assert.strictEqual(finalZIndex, 5000, 'custom zIndex applied');
+    });
+
+    test('Changing zIndex option to undefined resets the default pool zIndex', function(assert) {
+        const overlay = $('#overlay').dxOverlay({
+            visible: true,
+            zIndex: 5000
+        }).dxOverlay('instance');
+
+        const initialZIndex = Number(getComputedStyle(overlay.$content()[0]).zIndex);
+
+        assert.strictEqual(initialZIndex, 5000, 'overlay has custom zIndex');
+
+        overlay.option('zIndex', undefined);
+
+        const finalZIndex = Number(getComputedStyle(overlay.$content()[0]).zIndex);
+
+        assert.strictEqual(finalZIndex, 1501, 'initial pool zIndex applied');
+    });
 });