diff --git a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
index dfbe99c8de..bbbb4fd872 100644
--- a/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
+++ b/apps/api/src/app/portfolio/calculator/portfolio-calculator.ts
@@ -794,15 +794,20 @@ export abstract class PortfolioCalculator {
 
     const chart: HistoricalDataItem[] = [];
 
+    let grossPerformanceWithCurrencyEffectAtStartDate: number;
     let netPerformanceAtStartDate: number;
     let netPerformanceWithCurrencyEffectAtStartDate: number;
-    const totalInvestmentValuesWithCurrencyEffect: number[] = [];
+    const timeWeightedInvestmentValuesWithCurrencyEffect: number[] = [];
 
     for (const historicalDataItem of historicalData) {
       const date = resetHours(parseDate(historicalDataItem.date));
 
       if (!isBefore(date, start) && !isAfter(date, end)) {
         if (!isNumber(netPerformanceAtStartDate)) {
+          grossPerformanceWithCurrencyEffectAtStartDate =
+            historicalDataItem.valueWithCurrencyEffect -
+            historicalDataItem.totalInvestmentValueWithCurrencyEffect;
+
           netPerformanceAtStartDate = historicalDataItem.netPerformance;
 
           netPerformanceWithCurrencyEffectAtStartDate =
@@ -817,15 +822,18 @@ export abstract class PortfolioCalculator {
           netPerformanceWithCurrencyEffectAtStartDate;
 
         if (historicalDataItem.totalInvestmentValueWithCurrencyEffect > 0) {
-          totalInvestmentValuesWithCurrencyEffect.push(
-            historicalDataItem.totalInvestmentValueWithCurrencyEffect
+          // The invested capital in the date range is the value at its start
+          // date: the investment plus the gross performance up to that date
+          timeWeightedInvestmentValuesWithCurrencyEffect.push(
+            historicalDataItem.totalInvestmentValueWithCurrencyEffect +
+              grossPerformanceWithCurrencyEffectAtStartDate
           );
         }
 
         const timeWeightedInvestmentValue =
-          totalInvestmentValuesWithCurrencyEffect.length > 0
-            ? sum(totalInvestmentValuesWithCurrencyEffect) /
-              totalInvestmentValuesWithCurrencyEffect.length
+          timeWeightedInvestmentValuesWithCurrencyEffect.length > 0
+            ? sum(timeWeightedInvestmentValuesWithCurrencyEffect) /
+              timeWeightedInvestmentValuesWithCurrencyEffect.length
             : 0;
 
         chart.push({
diff --git a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-btcusd-buy-and-sell-partially.spec.ts b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-btcusd-buy-and-sell-partially.spec.ts
index e54fd96aa7..904f1361e6 100644
--- a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-btcusd-buy-and-sell-partially.spec.ts
+++ b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-btcusd-buy-and-sell-partially.spec.ts
@@ -190,10 +190,14 @@ describe('PortfolioCalculator', () => {
             netPerformance: new Big('27172.74').mul(0.97373),
             netPerformancePercentage: new Big('42.41978276196153750666'),
             netPerformancePercentageWithCurrencyEffectMap: {
-              max: new Big('41.72313811883729606471')
+              '1d': new Big('-0.04016229506406263535'),
+              max: new Big('41.72313811883729606471'),
+              ytd: new Big('-0.04016229506406263535')
             },
             netPerformanceWithCurrencyEffectMap: {
-              max: new Big('26516.208701400000064086')
+              '1d': new Big('-556.443324'),
+              max: new Big('26516.208701400000064086'),
+              ytd: new Big('-556.443324')
             },
             quantity: new Big('1'),
             symbol: 'BTCUSD',
@@ -281,8 +285,8 @@ describe('PortfolioCalculator', () => {
         '1d': {
           date: '2018-01-01',
           netPerformance: -486.0860160000011,
-          netPerformanceInPercentage: -1.5259683109961866,
-          netPerformanceInPercentageWithCurrencyEffect: -1.7468407881319952,
+          netPerformanceInPercentage: -0.035084130151423504,
+          netPerformanceInPercentageWithCurrencyEffect: -0.040162295064062624,
           netPerformanceWithCurrencyEffect: -556.4433239999998,
           totalInvestmentValueWithCurrencyEffect: 318.54266729999995,
           valueWithCurrencyEffect: 13298.425356
@@ -299,8 +303,8 @@ describe('PortfolioCalculator', () => {
         ytd: {
           date: '2018-01-01',
           netPerformance: -486.0860160000011,
-          netPerformanceInPercentage: -1.5259683109961866,
-          netPerformanceInPercentageWithCurrencyEffect: -1.7468407881319952,
+          netPerformanceInPercentage: -0.035084130151423504,
+          netPerformanceInPercentageWithCurrencyEffect: -0.040162295064062624,
           netPerformanceWithCurrencyEffect: -556.4433239999998,
           totalInvestmentValueWithCurrencyEffect: 318.54266729999995,
           valueWithCurrencyEffect: 13298.425356
diff --git a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-msft-buy-with-dividend.spec.ts b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-msft-buy-with-dividend.spec.ts
index bb16af5ef6..87e13e75c9 100644
--- a/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-msft-buy-with-dividend.spec.ts
+++ b/apps/api/src/app/portfolio/calculator/roai/portfolio-calculator-msft-buy-with-dividend.spec.ts
@@ -193,8 +193,8 @@ describe('PortfolioCalculator', () => {
         '1d': {
           date: '2023-07-10',
           netPerformance: -5.390000000000001,
-          netPerformanceInPercentage: -0.018052113336459244,
-          netPerformanceInPercentageWithCurrencyEffect: -0.018052113336459244,
+          netPerformanceInPercentage: -0.015983630864124312,
+          netPerformanceInPercentageWithCurrencyEffect: -0.015983630864124312,
           netPerformanceWithCurrencyEffect: -5.390000000000001,
           totalInvestmentValueWithCurrencyEffect: 298.58,
           valueWithCurrencyEffect: 331.83
@@ -211,8 +211,8 @@ describe('PortfolioCalculator', () => {
         ytd: {
           date: '2023-07-10',
           netPerformance: -7.68,
-          netPerformanceInPercentage: -0.025721749614843515,
-          netPerformanceInPercentageWithCurrencyEffect: -0.025721749614843515,
+          netPerformanceInPercentage: -0.022620835910577012,
+          netPerformanceInPercentageWithCurrencyEffect: -0.022620835910577012,
           netPerformanceWithCurrencyEffect: -7.68,
           totalInvestmentValueWithCurrencyEffect: 298.58,
           valueWithCurrencyEffect: 331.83