From 8287c1c7ca162058495be50f4336d238bab45227 Mon Sep 17 00:00:00 2001
From: Thomas Kaul <4159106+dtslvr@users.noreply.github.com>
Date: Fri, 9 Oct 2026 17:10:22 +0200
Subject: [PATCH] Bugfix/end date of calendar year date ranges in portfolio
 performance (#8095)

* Fix end date of calendar year date ranges

* Update changelog
---
 CHANGELOG.md                                  |  1 +
 .../calculator/portfolio-calculator.ts        | 13 +++---
 .../roai/portfolio-calculator.spec.ts         | 44 +++++++++++++++++++
 3 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8d87e1535b..0a105dd492 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fixed the missing list numbers in the top and bottom holdings on the analysis page in Safari
 - Fixed the missing first data point in the portfolio evolution chart on the analysis page
+- Fixed the end date of calendar year date ranges in the portfolio performance calculation for instances in time zones with a negative UTC offset
 - Fixed the missing mapping for Korea in the country weightings of the _Financial Modeling Prep_ service
 
 ## 3.81.0 - 2026-10-07
diff --git a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
index 7a8bbcc741..ca440c6d2a 100644
--- a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
+++ b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
@@ -1407,7 +1407,7 @@ export abstract class PortfolioCalculator {
     return this.snapshot.totalLiabilitiesWithCurrencyEffect;
   }
 
-  public async getPerformance({ end, start }) {
+  public async getPerformance({ end, start }: { end: Date; start: Date }) {
     await this.snapshotPromise;
 
     const { historicalData } = this.snapshot;
@@ -1418,14 +1418,13 @@ export abstract class PortfolioCalculator {
     let netPerformanceAtStartDate: number;
     let netPerformanceWithCurrencyEffectAtStartDate: number;
 
-    const startDate = isEqual(start, endOfDay(start))
-      ? resetHours(start)
-      : start;
+    const endDate = this.toChartDate(end);
+    const startDate = this.toChartDate(start);
 
     for (const historicalDataItem of historicalData) {
       const date = resetHours(parseDate(historicalDataItem.date));
 
-      if (!isBefore(date, startDate) && !isAfter(date, end)) {
+      if (!isBefore(date, startDate) && !isAfter(date, endDate)) {
         // Take the values at the start date from the first day of the date
         // range
         if (historicalDataItemsOfDateRange.length === 0) {
@@ -1915,4 +1914,8 @@ export abstract class PortfolioCalculator {
       await this.initialize(attempt + 1);
     }
   }
+
+  private toChartDate(aDate: Date) {
+    return isEqual(aDate, endOfDay(aDate)) ? resetHours(aDate) : aDate;
+  }
 }
diff --git a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator.spec.ts b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator.spec.ts
index 5f8d9cdc44..43ff160a78 100644
--- a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator.spec.ts
+++ b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator.spec.ts
@@ -1,3 +1,7 @@
+/**
+ * @jest-environment <rootDir>/jest-environment-tz.js
+ * @jest-environment-options {"timeZone": "America/New_York"}
+ */
 import { PortfolioCalculator } from '@ghostfolio/api/app/portfolio/calculator/portfolio-calculator';
 import { userDummyData } from '@ghostfolio/api/app/portfolio/calculator/portfolio-calculator-test-utils';
 import { PortfolioCalculatorFactory } from '@ghostfolio/api/app/portfolio/calculator/portfolio-calculator.factory';
@@ -9,6 +13,7 @@ import { ConfigurationService } from '@ghostfolio/api/services/configuration/con
 import { ExchangeRateDataService } from '@ghostfolio/api/services/exchange-rate-data/exchange-rate-data.service';
 import { PortfolioSnapshotService } from '@ghostfolio/api/services/queues/portfolio-snapshot/portfolio-snapshot.service';
 import { PortfolioSnapshotServiceMock } from '@ghostfolio/api/services/queues/portfolio-snapshot/portfolio-snapshot.service.mock';
+import { getIntervalFromDateRange } from '@ghostfolio/common/calculation-helper';
 import { HistoricalDataItem } from '@ghostfolio/common/interfaces';
 import { PerformanceCalculationType } from '@ghostfolio/common/types/performance-calculation-type.type';
 
@@ -183,4 +188,43 @@ describe('PortfolioCalculator', () => {
       ).toBeCloseTo(0.23, 10);
     });
   });
+
+  describe('get performance', () => {
+    it('with a calendar year date range', async () => {
+      const snapshot = await portfolioCalculator.getSnapshot();
+
+      snapshot.historicalData = [
+        getHistoricalDataItem({
+          date: '2016-12-31',
+          investment: 100,
+          netPerformance: 0
+        }),
+        getHistoricalDataItem({
+          date: '2017-12-31',
+          investment: 100,
+          netPerformance: 10
+        }),
+        getHistoricalDataItem({
+          date: '2018-01-01',
+          investment: 100,
+          netPerformance: 20
+        })
+      ];
+
+      const { endDate, startDate } = getIntervalFromDateRange({
+        dateRange: '2017'
+      });
+
+      const { chart } = await portfolioCalculator.getPerformance({
+        end: endDate,
+        start: startDate
+      });
+
+      expect(
+        chart.map(({ date }) => {
+          return date;
+        })
+      ).toEqual(['2016-12-31', '2017-12-31']);
+    });
+  });
 });