diff --git a/CHANGELOG.md b/CHANGELOG.md
index 021e69a07..ab6db98a9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Improved the dynamic numerical precision for various values in the account detail dialog on mobile
 - Improved the dynamic numerical precision for various values in the holding detail dialog on mobile
+- Optimized the endpoint `GET api/v1/portfolio/holding/:dataSource/:symbol` by improving the processing of the historical market data
 
 ### Fixed
 
diff --git a/apps/api/src/services/data-provider/data-provider.service.ts b/apps/api/src/services/data-provider/data-provider.service.ts
index 1ea2d6436..5b54afb0b 100644
--- a/apps/api/src/services/data-provider/data-provider.service.ts
+++ b/apps/api/src/services/data-provider/data-provider.service.ts
@@ -385,10 +385,11 @@ export class DataProviderService implements OnModuleInit {
       response = marketDataByGranularity.reduce((r, marketData) => {
         const { date, marketPrice, symbol } = marketData;
 
-        r[symbol] = {
-          ...(r[symbol] || {}),
-          [format(new Date(date), DATE_FORMAT)]: { marketPrice }
-        };
+        if (!r[symbol]) {
+          r[symbol] = {};
+        }
+
+        r[symbol][format(new Date(date), DATE_FORMAT)] = { marketPrice };
 
         return r;
       }, {});