diff --git a/src/web-ui/src/features/market-account/MarketAccountControls.scss b/src/web-ui/src/features/market-account/MarketAccountControls.scss
index 78999f2a2..51b55632b 100644
--- a/src/web-ui/src/features/market-account/MarketAccountControls.scss
+++ b/src/web-ui/src/features/market-account/MarketAccountControls.scss
@@ -48,11 +48,13 @@
   }
 
   &__menu {
-    position: absolute;
-    z-index: 40;
-    top: calc(100% + #{$size-gap-2});
-    right: 0;
-    width: 230px;
+    position: fixed;
+    z-index: $z-popover;
+    width: max-content;
+    min-width: min(190px, calc(100vw - 16px));
+    max-width: min(230px, calc(100vw - 16px));
+    max-height: calc(100vh - 16px);
+    overflow-y: auto;
     padding: $size-gap-2;
     border: 1px solid var(--bf-appearance-token-border-base);
     border-radius: $size-radius-base;
diff --git a/src/web-ui/src/features/market-account/MarketAccountControls.test.tsx b/src/web-ui/src/features/market-account/MarketAccountControls.test.tsx
index 58e117c58..da39d8390 100644
--- a/src/web-ui/src/features/market-account/MarketAccountControls.test.tsx
+++ b/src/web-ui/src/features/market-account/MarketAccountControls.test.tsx
@@ -4,6 +4,7 @@ import React, { act } from 'react';
 import { createRoot } from 'react-dom/client';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { MarketAccountControls } from './MarketAccountControls';
+import { calculateMarketAccountMenuPosition } from './marketAccountMenuPosition';
 
 const mocks = vi.hoisted(() => ({
   account: {
@@ -77,6 +78,7 @@ describe('MarketAccountControls', () => {
   afterEach(() => {
     act(() => root.unmount());
     container.remove();
+    document.querySelector('[data-bf-overlay-host="true"]')?.remove();
   });
 
   it('opens the shared GitHub login dialog and starts the vault-backed flow', async () => {
@@ -102,9 +104,28 @@ describe('MarketAccountControls', () => {
 
     const trigger = container.querySelector<HTMLButtonElement>('[aria-haspopup="menu"]');
     await act(async () => trigger?.click());
-    const logout = container.querySelector<HTMLButtonElement>('[role="menuitem"]');
+    const menu = document.querySelector<HTMLElement>('[role="menu"]');
+    expect(menu?.parentElement?.getAttribute('data-bf-overlay-host')).toBe('true');
+    const logout = menu?.querySelector<HTMLButtonElement>('[role="menuitem"]');
     expect(logout?.textContent).toContain('market.signOut');
     await act(async () => logout?.click());
     expect(mocks.logout).toHaveBeenCalledOnce();
   });
+
+  it('keeps the portalled menu aligned to the trigger and inside the viewport', () => {
+    const position = calculateMarketAccountMenuPosition(
+      { top: 16, right: 218, bottom: 46 },
+      { width: 230, height: 112 },
+      { width: 240, height: 180 },
+    );
+
+    expect(position).toEqual({ top: 52, left: 8 });
+    expect(
+      calculateMarketAccountMenuPosition(
+        { top: 150, right: 218, bottom: 180 },
+        { width: 230, height: 112 },
+        { width: 240, height: 200 },
+      ),
+    ).toEqual({ top: 32, left: 8 });
+  });
 });
diff --git a/src/web-ui/src/features/market-account/MarketAccountControls.tsx b/src/web-ui/src/features/market-account/MarketAccountControls.tsx
index f27b674f9..8c762ab1f 100644
--- a/src/web-ui/src/features/market-account/MarketAccountControls.tsx
+++ b/src/web-ui/src/features/market-account/MarketAccountControls.tsx
@@ -1,6 +1,8 @@
-import { useEffect, useRef, useState } from 'react';
+import { useCallback, useEffect, useLayoutEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
 import { ChevronDown, Github, Loader2, LogOut } from 'lucide-react';
 import { Avatar, Button, Modal } from '@/component-library';
+import { getAppearanceOverlayHost } from '@/infrastructure/appearance/runtime/AppearanceOverlayHost';
 import { useI18n } from '@/infrastructure/i18n';
 import {
   MarketAccountError,
@@ -8,6 +10,10 @@ import {
   useMarketAccount,
 } from '@/infrastructure/market-account';
 import { useNotification } from '@/shared/notification-system';
+import {
+  calculateMarketAccountMenuPosition,
+  type MarketAccountMenuPosition,
+} from './marketAccountMenuPosition';
 import './MarketAccountControls.scss';
 
 export interface MarketAccountControlsProps {
@@ -28,8 +34,11 @@ export function MarketAccountControls({
   const account = useMarketAccount();
   const [internalLoginOpen, setInternalLoginOpen] = useState(false);
   const [menuOpen, setMenuOpen] = useState(false);
+  const [menuPosition, setMenuPosition] = useState<MarketAccountMenuPosition | null>(null);
   const menuRef = useRef<HTMLDivElement>(null);
+  const menuPanelRef = useRef<HTMLDivElement>(null);
   const menuTriggerRef = useRef<HTMLButtonElement>(null);
+  const menuPositionFrameRef = useRef<number | null>(null);
   const startedHere = useRef(false);
   const loginOpen = controlledLoginOpen ?? internalLoginOpen;
 
@@ -38,10 +47,53 @@ export function MarketAccountControls({
     onLoginOpenChange?.(open);
   };
 
+  const updateMenuPosition = useCallback(() => {
+    if (!menuTriggerRef.current || !menuPanelRef.current) return;
+    setMenuPosition(
+      calculateMarketAccountMenuPosition(
+        menuTriggerRef.current.getBoundingClientRect(),
+        menuPanelRef.current.getBoundingClientRect(),
+        { width: window.innerWidth, height: window.innerHeight },
+      ),
+    );
+  }, []);
+
+  const scheduleMenuPositionUpdate = useCallback(() => {
+    if (menuPositionFrameRef.current !== null) return;
+    menuPositionFrameRef.current = requestAnimationFrame(() => {
+      menuPositionFrameRef.current = null;
+      updateMenuPosition();
+    });
+  }, [updateMenuPosition]);
+
+  useLayoutEffect(() => {
+    if (!menuOpen) {
+      return;
+    }
+
+    updateMenuPosition();
+    window.addEventListener('resize', scheduleMenuPositionUpdate, { passive: true });
+    window.addEventListener('scroll', scheduleMenuPositionUpdate, {
+      capture: true,
+      passive: true,
+    });
+    return () => {
+      window.removeEventListener('resize', scheduleMenuPositionUpdate);
+      window.removeEventListener('scroll', scheduleMenuPositionUpdate, { capture: true });
+      if (menuPositionFrameRef.current !== null) {
+        cancelAnimationFrame(menuPositionFrameRef.current);
+        menuPositionFrameRef.current = null;
+      }
+    };
+  }, [menuOpen, scheduleMenuPositionUpdate, updateMenuPosition]);
+
   useEffect(() => {
     if (!menuOpen) return;
     const closeOnOutsideClick = (event: PointerEvent) => {
-      if (!menuRef.current?.contains(event.target as Node)) setMenuOpen(false);
+      const target = event.target as Node;
+      if (!menuRef.current?.contains(target) && !menuPanelRef.current?.contains(target)) {
+        setMenuOpen(false);
+      }
     };
     const closeOnEscape = (event: KeyboardEvent) => {
       if (event.key !== 'Escape') return;
@@ -126,12 +178,18 @@ export function MarketAccountControls({
             <span>@{account.me.user.login}</span>
             <ChevronDown size={13} aria-hidden="true" />
           </button>
-          {menuOpen && (
+          {menuOpen && createPortal(
             <div
+              ref={menuPanelRef}
               className="market-account-controls__menu"
               role="menu"
               data-bf-component="market-account-controls"
               data-bf-part="menu"
+              style={{
+                top: `${menuPosition?.top ?? 0}px`,
+                left: `${menuPosition?.left ?? 0}px`,
+                visibility: menuPosition ? 'visible' : 'hidden',
+              }}
             >
               <div
                 className="market-account-controls__profile"
@@ -155,7 +213,8 @@ export function MarketAccountControls({
                 <LogOut size={14} aria-hidden="true" />
                 {t('market.signOut')}
               </button>
-            </div>
+            </div>,
+            getAppearanceOverlayHost(),
           )}
         </div>
       ) : (
diff --git a/src/web-ui/src/features/market-account/marketAccountMenuPosition.ts b/src/web-ui/src/features/market-account/marketAccountMenuPosition.ts
new file mode 100644
index 000000000..869ef93a4
--- /dev/null
+++ b/src/web-ui/src/features/market-account/marketAccountMenuPosition.ts
@@ -0,0 +1,26 @@
+import {
+  computeFixedPopoverPositionInViewport,
+  type FixedPopoverViewport,
+} from '@/shared/utils/fixedPopoverViewport';
+
+export interface MarketAccountMenuPosition {
+  top: number;
+  left: number;
+}
+
+export function calculateMarketAccountMenuPosition(
+  triggerRect: Pick<DOMRect, 'top' | 'right' | 'bottom'>,
+  menuRect: Pick<DOMRect, 'width' | 'height'>,
+  viewport: FixedPopoverViewport,
+): MarketAccountMenuPosition {
+  return computeFixedPopoverPositionInViewport(
+    {
+      left: triggerRect.right - menuRect.width,
+      top: triggerRect.top,
+      bottom: triggerRect.bottom,
+    },
+    menuRect.width,
+    menuRect.height,
+    viewport,
+  );
+}