diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2e6feba4a..bb32902f0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fixed an issue in the annualized performance calculation
+- Fixed an issue with the exchange rate calculation by expanding the date range to cover the full day (start to end of day)
 
 ## 2.237.0 - 2026-02-08
 
diff --git a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
index 2e58a4ef5..553cb8c90 100644
--- a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
+++ b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
@@ -53,6 +53,7 @@ import {
   isBefore,
   isWithinInterval,
   min,
+  startOfDay,
   startOfYear,
   subDays
 } from 'date-fns';
@@ -162,8 +163,8 @@ export abstract class PortfolioCalculator {
       subDays(dateOfFirstActivity, 1)
     );
 
-    this.endDate = endDate;
-    this.startDate = startDate;
+    this.endDate = endOfDay(endDate);
+    this.startDate = startOfDay(startDate);
 
     this.computeTransactionPoints();
 
@@ -236,7 +237,7 @@ export abstract class PortfolioCalculator {
     const exchangeRatesByCurrency =
       await this.exchangeRateDataService.getExchangeRatesByCurrency({
         currencies: Array.from(new Set(Object.values(currencies))),
-        endDate: endOfDay(this.endDate),
+        endDate: this.endDate,
         startDate: this.startDate,
         targetCurrency: this.currency
       });