diff --git a/components/ExperimentTracker.tsx b/components/ExperimentTracker.tsx
index 42ade8a..9ca083d 100644
--- a/components/ExperimentTracker.tsx
+++ b/components/ExperimentTracker.tsx
@@ -11,6 +11,7 @@ export interface Experiment {
     id: string;
     week: string; // "2026-08" matching YYYY-WW format used in pivot data
     product_line: string;
+    marketplace: string; // e.g. "Amazon DE", "Amazon UK"
     action_type: 'SEO' | 'Price' | 'Advertising' | 'Images' | 'A+ Content' | 'Variants' | 'Stock' | 'Other';
     description: string;
     expected_impact: 'More Sales' | 'Better Visibility' | 'Lower Costs';
@@ -93,6 +94,7 @@ interface ExperimentTrackerProps {
     rows: WeeklyPivotRow[];
     weeks: string[]; // sorted descending (most recent first)
     primaryMetric: 'units' | 'revenue';
+    customerFilters: string[]; // active marketplace filters from parent
 }
 
 // --- Custom dot for experiment markers ---
@@ -150,6 +152,7 @@ const ChartTooltipContent: React.FC<any> = ({ active, payload, label, experiment
                                     {exp.action_type}
                                 </span>
                                 <span className="text-[10px] text-white/70 ml-1.5">{exp.product_line}</span>
+                                {exp.marketplace && <span className="text-[9px] text-slate-500 ml-1">({exp.marketplace})</span>}
                                 <p className="text-[10px] text-slate-400 mt-0.5 leading-tight">{exp.description}</p>
                             </div>
                         </div>
@@ -162,7 +165,7 @@ const ChartTooltipContent: React.FC<any> = ({ active, payload, label, experiment
 
 // --- Main Component ---
 
-const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, primaryMetric }) => {
+const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, primaryMetric, customerFilters }) => {
     const [experiments, setExperiments] = useState<Experiment[]>(loadExperiments);
     const [showForm, setShowForm] = useState(false);
     const [showPanel, setShowPanel] = useState(true);
@@ -171,10 +174,24 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
     // Form state
     const [formWeek, setFormWeek] = useState(getCurrentWeek);
     const [formLine, setFormLine] = useState('');
+    const [formMarketplace, setFormMarketplace] = useState('');
     const [formAction, setFormAction] = useState<ActionType>('SEO');
     const [formDesc, setFormDesc] = useState('');
     const [formImpact, setFormImpact] = useState<ExpectedImpact>('More Sales');
 
+    // Available marketplaces from data
+    const marketplaces = useMemo(() => {
+        const mks = new Set(rows.map(r => r.customer).filter(Boolean));
+        return Array.from(mks).sort();
+    }, [rows]);
+
+    // Default marketplace to active filter when opening form
+    const defaultMarketplace = useMemo(() => {
+        if (customerFilters.length === 1) return customerFilters[0];
+        if (customerFilters.length > 0) return customerFilters[0];
+        return marketplaces[0] || '';
+    }, [customerFilters, marketplaces]);
+
     // Available product lines from data
     const productLines = useMemo(() => {
         const lines = new Set(rows.map(r => r.line).filter(Boolean));
@@ -218,6 +235,7 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
             let total = 0;
             for (const row of rows) {
                 if (row.line !== exp.product_line) continue;
+                if (exp.marketplace && row.customer !== exp.marketplace) continue;
                 total += primaryMetric === 'units'
                     ? (row.unitsByWeek[w] || 0)
                     : (row.revenueByWeek[w] || 0);
@@ -252,12 +270,13 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
     }, []);
 
     const handleSubmit = useCallback(() => {
-        if (!formLine || !formDesc.trim()) return;
+        if (!formLine || !formMarketplace || !formDesc.trim()) return;
 
         const newExp: Experiment = {
             id: `exp_${Date.now()}`,
             week: formWeek,
             product_line: formLine,
+            marketplace: formMarketplace,
             action_type: formAction,
             description: formDesc.trim(),
             expected_impact: formImpact,
@@ -269,7 +288,7 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
         setShowForm(false);
         setFormDesc('');
         setFormWeek(getCurrentWeek());
-    }, [formWeek, formLine, formAction, formDesc, formImpact, experiments, updateExperiments]);
+    }, [formWeek, formLine, formMarketplace, formAction, formDesc, formImpact, experiments, updateExperiments]);
 
     const handleStatusChange = useCallback((id: string, newStatus: ExperimentStatus) => {
         updateExperiments(experiments.map(e => e.id === id ? { ...e, status: newStatus } : e));
@@ -299,7 +318,7 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
                     </div>
                 </div>
                 <button
-                    onClick={() => setShowForm(true)}
+                    onClick={() => { setFormMarketplace(defaultMarketplace); setShowForm(true); }}
                     className="flex items-center gap-2 bg-indigo-600 hover:bg-indigo-500 text-white px-4 py-2 rounded-lg text-xs font-bold transition-colors border border-indigo-500/50 shadow-lg shadow-indigo-500/20"
                 >
                     <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -417,6 +436,21 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
                                 </select>
                             </div>
 
+                            {/* Marketplace */}
+                            <div>
+                                <label className="text-[10px] font-black text-slate-400 uppercase tracking-widest block mb-1.5">Marketplace</label>
+                                <select
+                                    value={formMarketplace}
+                                    onChange={e => setFormMarketplace(e.target.value)}
+                                    className="w-full bg-slate-950 border border-white/10 rounded-lg px-3 py-2 text-sm text-white focus:outline-none focus:ring-2 focus:ring-indigo-500"
+                                >
+                                    <option value="">Select marketplace...</option>
+                                    {marketplaces.map(mk => (
+                                        <option key={mk} value={mk}>{mk}</option>
+                                    ))}
+                                </select>
+                            </div>
+
                             {/* Action Type */}
                             <div>
                                 <label className="text-[10px] font-black text-slate-400 uppercase tracking-widest block mb-1.5">Action Type</label>
@@ -478,7 +512,7 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
                             </button>
                             <button
                                 onClick={handleSubmit}
-                                disabled={!formLine || !formDesc.trim()}
+                                disabled={!formLine || !formMarketplace || !formDesc.trim()}
                                 className="px-5 py-2 rounded-lg text-xs font-bold text-white bg-indigo-600 hover:bg-indigo-500 border border-indigo-500/50 shadow-lg shadow-indigo-500/20 transition-colors disabled:opacity-40 disabled:cursor-not-allowed"
                             >
                                 Save Experiment
@@ -507,10 +541,11 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
 
                     {showPanel && (
                         <div className="overflow-x-auto border-t border-white/5">
-                            <table className="w-full text-left border-collapse min-w-[800px]">
+                            <table className="w-full text-left border-collapse min-w-[900px]">
                                 <thead>
                                     <tr className="border-b border-white/10">
                                         <th className="p-2.5 px-4 text-[10px] font-black text-slate-500 uppercase tracking-widest">Week</th>
+                                        <th className="p-2.5 px-4 text-[10px] font-black text-slate-500 uppercase tracking-widest">Marketplace</th>
                                         <th className="p-2.5 px-4 text-[10px] font-black text-slate-500 uppercase tracking-widest">Product Line</th>
                                         <th className="p-2.5 px-4 text-[10px] font-black text-slate-500 uppercase tracking-widest">Action</th>
                                         <th className="p-2.5 px-4 text-[10px] font-black text-slate-500 uppercase tracking-widest">Description</th>
@@ -528,6 +563,9 @@ const ExperimentTracker: React.FC<ExperimentTrackerProps> = ({ rows, weeks, prim
                                                 <td className="p-2.5 px-4 text-xs font-bold text-white whitespace-nowrap">
                                                     W{exp.week.split('-')[1]}/{exp.week.split('-')[0].slice(-2)}
                                                 </td>
+                                                <td className="p-2.5 px-4">
+                                                    <span className="text-[10px] text-sky-400 font-bold">{exp.marketplace || '—'}</span>
+                                                </td>
                                                 <td className="p-2.5 px-4">
                                                     <span className="text-[10px] text-fuchsia-400 font-bold uppercase tracking-widest">{exp.product_line}</span>
                                                 </td>
diff --git a/components/WeeklyGrid.tsx b/components/WeeklyGrid.tsx
index 78f3a20..81d8a96 100644
--- a/components/WeeklyGrid.tsx
+++ b/components/WeeklyGrid.tsx
@@ -666,7 +666,7 @@ const WeeklyGrid: React.FC<WeeklyGridProps & { top50Mode: 'eu' | 'uk' }> = ({
     return (
         <div className="flex flex-col gap-3 md:gap-4 animate-fade-in px-1 md:px-0">
             {/* Experiment Tracker */}
-            <ExperimentTracker rows={rows} weeks={weeks} primaryMetric={primaryMetric} />
+            <ExperimentTracker rows={rows} weeks={weeks} primaryMetric={primaryMetric} customerFilters={customerFilters} />
 
             {/* Toolbar: Search & Pagination */}
             <div className="flex flex-col lg:flex-row justify-between items-center gap-3 md:gap-4 bg-slate-900 border border-white/10 p-2 md:p-4 rounded-xl shadow-lg">