diff --git a/src/dotnet/QuantEngine.Application/Services/KisDataCollectionOrchestrator.cs b/src/dotnet/QuantEngine.Application/Services/KisDataCollectionOrchestrator.cs
index 6b3f6764..c6da4209 100644
--- a/src/dotnet/QuantEngine.Application/Services/KisDataCollectionOrchestrator.cs
+++ b/src/dotnet/QuantEngine.Application/Services/KisDataCollectionOrchestrator.cs
@@ -56,26 +56,53 @@ public class KisDataCollectionOrchestrator : ICollectionOrchestrator
                 try
                 {
                     _logger.LogInformation("Collecting ticker {Ticker} (run {RunId})", ticker, runId);
-                    var kisResult = await kisSource.GetPriceDataAsync(ticker, account);
 
-                    var seedRow = new Dictionary<string, object> { { "Ticker", ticker } };
-                    var (normalized, provenance) = _normalizer.NormalizeCollectionRow(seedRow, kisResult, null, false);
+                    CollectionSnapshotRecord? cachedSnapshot = null;
+                    if (IsMarketClosed())
+                    {
+                        var latest = await _repository.GetLatestSnapshotsForTickerAsync(ticker, 1);
+                        var todayPrefix = DateTime.UtcNow.AddHours(9).ToString("yyyy-MM-dd");
+                        if (latest.Count > 0 && latest[0].CapturedAt.StartsWith(todayPrefix))
+                        {
+                            cachedSnapshot = latest[0];
+                        }
+                    }
+
+                    Dictionary<string, object> normalized;
+                    string sourceName;
+
+                    if (cachedSnapshot != null)
+                    {
+                        _logger.LogInformation("Cache hit for ticker {Ticker} (run {RunId})", ticker, runId);
+                        normalized = JsonSerializer.Deserialize<Dictionary<string, object>>(cachedSnapshot.PayloadJson) 
+                                     ?? new Dictionary<string, object>();
+                        sourceName = cachedSnapshot.SourceName.EndsWith(" (Cached)") 
+                            ? cachedSnapshot.SourceName 
+                            : cachedSnapshot.SourceName + " (Cached)";
+                    }
+                    else
+                    {
+                        var kisResult = await kisSource.GetPriceDataAsync(ticker, account);
+                        var seedRow = new Dictionary<string, object> { { "Ticker", ticker } };
+                        var (norm, provenance) = _normalizer.NormalizeCollectionRow(seedRow, kisResult, null, false);
+                        normalized = norm;
+                        sourceName = (string)(provenance.GetValueOrDefault("source") ?? "kis_open_api");
+                    }
 
                     // Save to DB
                     await _repository.SaveSnapshotAsync(new CollectionSnapshotRecord(
                         RunId: runId,
                         DatasetName: "data_feed",
                         Ticker: ticker,
-                        SourceName: (string)(provenance.GetValueOrDefault("source") ?? "kis_open_api"),
+                        SourceName: sourceName,
                         PayloadJson: JsonSerializer.Serialize(normalized),
                         CapturedAt: DataNormalizationHelper.KstNowIso()
                     ));
 
                     // Track source
-                    var source = (string)(provenance.GetValueOrDefault("source") ?? "kis_open_api");
-                    if (!sourceCounts.ContainsKey(source))
-                        sourceCounts[source] = 0;
-                    sourceCounts[source]++;
+                    if (!sourceCounts.ContainsKey(sourceName))
+                        sourceCounts[sourceName] = 0;
+                    sourceCounts[sourceName]++;
 
                     rows.Add(normalized);
                     result.SuccessCount++;
@@ -176,6 +203,23 @@ public class KisDataCollectionOrchestrator : ICollectionOrchestrator
 
         return Path.Combine(Path.GetTempPath(), "kis_dotnet_collection_v1.json");
     }
+
+    private static bool IsMarketClosed()
+    {
+        // KST Time conversion (UTC+9)
+        var kst = DateTime.UtcNow.AddHours(9);
+        
+        // Weekend check
+        if (kst.DayOfWeek == DayOfWeek.Saturday || kst.DayOfWeek == DayOfWeek.Sunday)
+            return true;
+
+        // Market hours check (09:00 - 15:30)
+        var time = kst.TimeOfDay;
+        if (time < new TimeSpan(9, 0, 0) || time > new TimeSpan(15, 30, 0))
+            return true;
+
+        return false;
+    }
 }