Time weighted portfolio performance calculation (#2778)

* Implement time weighted portfolio performance calculation

* Update changelog

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Changed the performance calculation to a time-weighted approach
 - Used the `HasPermission` annotation in endpoints
 
 ## 2.32.0 - 2023-12-26

apps/api/src/app/portfolio/portfolio-calculator-baln-buy-and-sell.spec.ts

@@ -92,6 +92,7 @@ describe('PortfolioCalculator', () => {
             marketPrice: 148.9,
             quantity: new Big('0'),
             symbol: 'BALN.SW',
+            timeWeightedInvestment: new Big('285.8'),
             transactionCount: 2
           }
         ],

apps/api/src/app/portfolio/portfolio-calculator-baln-buy.spec.ts

@@ -81,6 +81,7 @@ describe('PortfolioCalculator', () => {
             marketPrice: 148.9,
             quantity: new Big('2'),
             symbol: 'BALN.SW',
+            timeWeightedInvestment: new Big('273.2'),
             transactionCount: 1
           }
         ],

apps/api/src/app/portfolio/portfolio-calculator-btcusd-buy-and-sell-partially.spec.ts

@@ -73,10 +73,10 @@ describe('PortfolioCalculator', () => {
         currentValue: new Big('13657.2'),
         errors: [],
         grossPerformance: new Big('27172.74'),
-        grossPerformancePercentage: new Big('42.40043067128546016291'),
+        grossPerformancePercentage: new Big('42.41978276196153750666'),
         hasErrors: false,
         netPerformance: new Big('27172.74'),
-        netPerformancePercentage: new Big('42.40043067128546016291'),
+        netPerformancePercentage: new Big('42.41978276196153750666'),
         positions: [
           {
             averagePrice: new Big('320.43'),
@@ -85,13 +85,14 @@ describe('PortfolioCalculator', () => {
             fee: new Big('0'),
             firstBuyDate: '2015-01-01',
             grossPerformance: new Big('27172.74'),
-            grossPerformancePercentage: new Big('42.40043067128546016291'),
+            grossPerformancePercentage: new Big('42.41978276196153750666'),
             investment: new Big('320.43'),
             netPerformance: new Big('27172.74'),
-            netPerformancePercentage: new Big('42.40043067128546016291'),
+            netPerformancePercentage: new Big('42.41978276196153750666'),
             marketPrice: 13657.2,
             quantity: new Big('1'),
             symbol: 'BTCUSD',
+            timeWeightedInvestment: new Big('640.56763686131386861314'),
             transactionCount: 2
           }
         ],

apps/api/src/app/portfolio/portfolio-calculator-novn-buy-and-sell-partially.spec.ts

@@ -73,10 +73,10 @@ describe('PortfolioCalculator', () => {
         currentValue: new Big('87.8'),
         errors: [],
         grossPerformance: new Big('21.93'),
-        grossPerformancePercentage: new Big('0.14465699208443271768'),
+        grossPerformancePercentage: new Big('0.15113417083448194384'),
         hasErrors: false,
         netPerformance: new Big('17.68'),
-        netPerformancePercentage: new Big('0.11662269129287598945'),
+        netPerformancePercentage: new Big('0.12184460284330327256'),
         positions: [
           {
             averagePrice: new Big('75.80'),
@@ -85,13 +85,14 @@ describe('PortfolioCalculator', () => {
             fee: new Big('4.25'),
             firstBuyDate: '2022-03-07',
             grossPerformance: new Big('21.93'),
-            grossPerformancePercentage: new Big('0.14465699208443271768'),
+            grossPerformancePercentage: new Big('0.15113417083448194384'),
             investment: new Big('75.80'),
             netPerformance: new Big('17.68'),
-            netPerformancePercentage: new Big('0.11662269129287598945'),
+            netPerformancePercentage: new Big('0.12184460284330327256'),
             marketPrice: 87.8,
             quantity: new Big('1'),
             symbol: 'NOVN.SW',
+            timeWeightedInvestment: new Big('145.10285714285714285714'),
             transactionCount: 2
           }
         ],

apps/api/src/app/portfolio/portfolio-calculator-novn-buy-and-sell.spec.ts

@@ -112,6 +112,7 @@ describe('PortfolioCalculator', () => {
             marketPrice: 87.8,
             quantity: new Big('0'),
             symbol: 'NOVN.SW',
+            timeWeightedInvestment: new Big('151.6'),
             transactionCount: 2
           }
         ],

apps/api/src/app/portfolio/portfolio-calculator.ts

@@ -15,6 +15,7 @@ import {
   addMilliseconds,
   addMonths,
   addYears,
+  differenceInDays,
   endOfDay,
   format,
   isAfter,
@@ -43,7 +44,7 @@ import { TransactionPointSymbol } from './interfaces/transaction-point-symbol.in
 import { TransactionPoint } from './interfaces/transaction-point.interface';
 
 export class PortfolioCalculator {
-  private static readonly CALCULATE_PERCENTAGE_PERFORMANCE_WITH_MAX_INVESTMENT =
+  private static readonly CALCULATE_PERCENTAGE_PERFORMANCE_WITH_TIME_WEIGHTED_INVESTMENT =
     true;
 
   private static readonly ENABLE_LOGGING = false;
@@ -238,12 +239,13 @@ export class PortfolioCalculator {
       }
     }
 
-    const valuesByDate: {
+    const accumulatedValuesByDate: {
       [date: string]: {
         maxTotalInvestmentValue: Big;
         totalCurrentValue: Big;
         totalInvestmentValue: Big;
         totalNetPerformanceValue: Big;
+        totalTimeWeightedInvestmentValue: Big;
       };
     } = {};
 
@@ -253,6 +255,7 @@ export class PortfolioCalculator {
         investmentValues: { [date: string]: Big };
         maxInvestmentValues: { [date: string]: Big };
         netPerformanceValues: { [date: string]: Big };
+        timeWeightedInvestmentValues: { [date: string]: Big };
       };
     } = {};
 
@@ -261,7 +264,8 @@ export class PortfolioCalculator {
         currentValues,
         investmentValues,
         maxInvestmentValues,
-        netPerformanceValues
+        netPerformanceValues,
+        timeWeightedInvestmentValues
       } = this.getSymbolMetrics({
         end,
         marketSymbolMap,
@@ -275,7 +279,8 @@ export class PortfolioCalculator {
         currentValues,
         investmentValues,
         maxInvestmentValues,
-        netPerformanceValues
+        netPerformanceValues,
+        timeWeightedInvestmentValues
       };
     }
 
@@ -293,38 +298,50 @@ export class PortfolioCalculator {
           symbolValues.maxInvestmentValues?.[dateString] ?? new Big(0);
         const netPerformanceValue =
           symbolValues.netPerformanceValues?.[dateString] ?? new Big(0);
+        const timeWeightedInvestmentValue =
+          symbolValues.timeWeightedInvestmentValues?.[dateString] ?? new Big(0);
 
-        valuesByDate[dateString] = {
+        accumulatedValuesByDate[dateString] = {
           totalCurrentValue: (
-            valuesByDate[dateString]?.totalCurrentValue ?? new Big(0)
+            accumulatedValuesByDate[dateString]?.totalCurrentValue ?? new Big(0)
           ).add(currentValue),
           totalInvestmentValue: (
-            valuesByDate[dateString]?.totalInvestmentValue ?? new Big(0)
+            accumulatedValuesByDate[dateString]?.totalInvestmentValue ??
+            new Big(0)
           ).add(investmentValue),
+          totalTimeWeightedInvestmentValue: (
+            accumulatedValuesByDate[dateString]
+              ?.totalTimeWeightedInvestmentValue ?? new Big(0)
+          ).add(timeWeightedInvestmentValue),
           maxTotalInvestmentValue: (
-            valuesByDate[dateString]?.maxTotalInvestmentValue ?? new Big(0)
+            accumulatedValuesByDate[dateString]?.maxTotalInvestmentValue ??
+            new Big(0)
           ).add(maxInvestmentValue),
           totalNetPerformanceValue: (
-            valuesByDate[dateString]?.totalNetPerformanceValue ?? new Big(0)
+            accumulatedValuesByDate[dateString]?.totalNetPerformanceValue ??
+            new Big(0)
           ).add(netPerformanceValue)
         };
       }
     }
 
-    return Object.entries(valuesByDate).map(([date, values]) => {
+    return Object.entries(accumulatedValuesByDate).map(([date, values]) => {
       const {
         maxTotalInvestmentValue,
         totalCurrentValue,
         totalInvestmentValue,
-        totalNetPerformanceValue
+        totalNetPerformanceValue,
+        totalTimeWeightedInvestmentValue
       } = values;
 
-      const netPerformanceInPercentage = maxTotalInvestmentValue.eq(0)
+      let investmentValue =
+        PortfolioCalculator.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_TIME_WEIGHTED_INVESTMENT
+          ? totalTimeWeightedInvestmentValue
+          : maxTotalInvestmentValue;
+
+      const netPerformanceInPercentage = investmentValue.eq(0)
         ? 0
-        : totalNetPerformanceValue
+        : totalNetPerformanceValue.div(investmentValue).mul(100).toNumber();
-            .div(maxTotalInvestmentValue)
-            .mul(100)
-            .toNumber();
 
       return {
         date,
@@ -447,7 +464,6 @@ export class PortfolioCalculator {
     if (firstIndex > 0) {
       firstIndex--;
     }
-    const initialValues: { [symbol: string]: Big } = {};
 
     const positions: TimelinePosition[] = [];
     let hasAnySymbolMetricsErrors = false;
@@ -461,9 +477,9 @@ export class PortfolioCalculator {
         grossPerformance,
         grossPerformancePercentage,
         hasErrors,
-        initialValue,
         netPerformance,
-        netPerformancePercentage
+        netPerformancePercentage,
+        timeWeightedInvestment
       } = this.getSymbolMetrics({
         end,
         marketSymbolMap,
@@ -472,9 +488,9 @@ export class PortfolioCalculator {
       });
 
       hasAnySymbolMetricsErrors = hasAnySymbolMetricsErrors || hasErrors;
-      initialValues[item.symbol] = initialValue;
 
       positions.push({
+        timeWeightedInvestment,
         averagePrice: item.quantity.eq(0)
           ? new Big(0)
           : item.investment.div(item.quantity),
@@ -509,7 +525,7 @@ export class PortfolioCalculator {
       }
     }
 
-    const overall = this.calculateOverallPerformance(positions, initialValues);
+    const overall = this.calculateOverallPerformance(positions);
 
     return {
       ...overall,
@@ -732,18 +748,13 @@ export class PortfolioCalculator {
     };
   }
 
-  private calculateOverallPerformance(
+  private calculateOverallPerformance(positions: TimelinePosition[]) {
-    positions: TimelinePosition[],
-    initialValues: { [symbol: string]: Big }
-  ) {
     let currentValue = new Big(0);
     let grossPerformance = new Big(0);
-    let grossPerformancePercentage = new Big(0);
     let hasErrors = false;
     let netPerformance = new Big(0);
-    let netPerformancePercentage = new Big(0);
-    let sumOfWeights = new Big(0);
     let totalInvestment = new Big(0);
+    let totalTimeWeightedInvestment = new Big(0);
 
     for (const currentPosition of positions) {
       if (currentPosition.marketPrice) {
@@ -766,21 +777,9 @@ export class PortfolioCalculator {
         hasErrors = true;
       }
 
-      if (currentPosition.grossPerformancePercentage) {
+      if (currentPosition.timeWeightedInvestment) {
-        // Use the average from the initial value and the current investment as
+        totalTimeWeightedInvestment = totalTimeWeightedInvestment.plus(
-        // a weight
+          currentPosition.timeWeightedInvestment
-        const weight = (initialValues[currentPosition.symbol] ?? new Big(0))
-          .plus(currentPosition.investment)
-          .div(2);
-
-        sumOfWeights = sumOfWeights.plus(weight);
-
-        grossPerformancePercentage = grossPerformancePercentage.plus(
-          currentPosition.grossPerformancePercentage.mul(weight)
-        );
-
-        netPerformancePercentage = netPerformancePercentage.plus(
-          currentPosition.netPerformancePercentage.mul(weight)
         );
       } else if (!currentPosition.quantity.eq(0)) {
         Logger.warn(
@@ -791,22 +790,18 @@ export class PortfolioCalculator {
       }
     }
 
-    if (sumOfWeights.gt(0)) {
-      grossPerformancePercentage = grossPerformancePercentage.div(sumOfWeights);
-      netPerformancePercentage = netPerformancePercentage.div(sumOfWeights);
-    } else {
-      grossPerformancePercentage = new Big(0);
-      netPerformancePercentage = new Big(0);
-    }
-
     return {
       currentValue,
       grossPerformance,
-      grossPerformancePercentage,
       hasErrors,
       netPerformance,
-      netPerformancePercentage,
+      totalInvestment,
-      totalInvestment
+      netPerformancePercentage: totalTimeWeightedInvestment.eq(0)
+        ? new Big(0)
+        : netPerformance.div(totalTimeWeightedInvestment),
+      grossPerformancePercentage: totalTimeWeightedInvestment.eq(0)
+        ? new Big(0)
+        : grossPerformance.div(totalTimeWeightedInvestment)
     };
   }
 
@@ -1018,6 +1013,7 @@ export class PortfolioCalculator {
 
     let averagePriceAtEndDate = new Big(0);
     let averagePriceAtStartDate = new Big(0);
+    const currentValues: { [date: string]: Big } = {};
     let feesAtStartDate = new Big(0);
     let fees = new Big(0);
     let grossPerformance = new Big(0);
@@ -1025,12 +1021,12 @@ export class PortfolioCalculator {
     let grossPerformanceFromSells = new Big(0);
     let initialValue: Big;
     let investmentAtStartDate: Big;
-    const currentValues: { [date: string]: Big } = {};
     const investmentValues: { [date: string]: Big } = {};
     const maxInvestmentValues: { [date: string]: Big } = {};
     let lastAveragePrice = new Big(0);
     let maxTotalInvestment = new Big(0);
     const netPerformanceValues: { [date: string]: Big } = {};
+    const timeWeightedInvestmentValues: { [date: string]: Big } = {};
     let totalInvestment = new Big(0);
     let totalInvestmentWithGrossPerformanceFromSell = new Big(0);
     let totalUnits = new Big(0);
@@ -1122,6 +1118,9 @@ export class PortfolioCalculator {
       return order.itemType === 'end';
     });
 
+    let totalInvestmentDays = 0;
+    let sumOfTimeWeightedInvestments = new Big(0);
+
     for (let i = 0; i < orders.length; i += 1) {
       const order = orders[i];
 
@@ -1162,11 +1161,11 @@ export class PortfolioCalculator {
         order.type === 'BUY'
           ? order.quantity.mul(order.unitPrice).mul(this.getFactor(order.type))
           : totalUnits.gt(0)
-          ? totalInvestment
+            ? totalInvestment
-              .div(totalUnits)
+                .div(totalUnits)
-              .mul(order.quantity)
+                .mul(order.quantity)
-              .mul(this.getFactor(order.type))
+                .mul(this.getFactor(order.type))
-          : new Big(0);
+            : new Big(0);
 
       if (PortfolioCalculator.ENABLE_LOGGING) {
         console.log('totalInvestment', totalInvestment.toNumber());
@@ -1174,6 +1173,7 @@ export class PortfolioCalculator {
         console.log('transactionInvestment', transactionInvestment.toNumber());
       }
 
+      const totalInvestmentBeforeTransaction = totalInvestment;
       totalInvestment = totalInvestment.plus(transactionInvestment);
 
       if (i >= indexOfStartOrder && totalInvestment.gt(maxTotalInvestment)) {
@@ -1243,14 +1243,48 @@ export class PortfolioCalculator {
         grossPerformanceAtStartDate = grossPerformance;
       }
 
-      if (isChartMode && i > indexOfStartOrder) {
+      if (i > indexOfStartOrder) {
-        currentValues[order.date] = valueOfInvestment;
+        // Only consider periods with an investment for the calculation of
-        netPerformanceValues[order.date] = grossPerformance
+        // the time weighted investment
-          .minus(grossPerformanceAtStartDate)
+        if (totalInvestmentBeforeTransaction.gt(0)) {
-          .minus(fees.minus(feesAtStartDate));
+          // Calculate the number of days since the previous order
+          const orderDate = new Date(order.date);
+          const previousOrderDate = new Date(orders[i - 1].date);
+
+          let daysSinceLastOrder = differenceInDays(
+            orderDate,
+            previousOrderDate
+          );
+
+          // Set to at least 1 day, otherwise the transactions on the same day
+          // would not be considered in the time weighted calculation
+          if (daysSinceLastOrder <= 0) {
+            daysSinceLastOrder = 1;
+          }
+
+          // Sum up the total investment days since the start date to calculate
+          // the time weighted investment
+          totalInvestmentDays += daysSinceLastOrder;
 
-        investmentValues[order.date] = totalInvestment;
+          sumOfTimeWeightedInvestments = sumOfTimeWeightedInvestments.add(
-        maxInvestmentValues[order.date] = maxTotalInvestment;
+            totalInvestmentBeforeTransaction.mul(daysSinceLastOrder)
+          );
+        }
+
+        if (isChartMode) {
+          currentValues[order.date] = valueOfInvestment;
+          netPerformanceValues[order.date] = grossPerformance
+            .minus(grossPerformanceAtStartDate)
+            .minus(fees.minus(feesAtStartDate));
+
+          investmentValues[order.date] = totalInvestment;
+          maxInvestmentValues[order.date] = maxTotalInvestment;
+
+          timeWeightedInvestmentValues[order.date] =
+            totalInvestmentDays > 0
+              ? sumOfTimeWeightedInvestments.div(totalInvestmentDays)
+              : new Big(0);
+        }
       }
 
       if (PortfolioCalculator.ENABLE_LOGGING) {
@@ -1274,50 +1308,79 @@ export class PortfolioCalculator {
       .minus(grossPerformanceAtStartDate)
       .minus(fees.minus(feesAtStartDate));
 
+    const timeWeightedAverageInvestmentBetweenStartAndEndDate =
+      totalInvestmentDays > 0
+        ? sumOfTimeWeightedInvestments.div(totalInvestmentDays)
+        : new Big(0);
+
     const maxInvestmentBetweenStartAndEndDate = valueAtStartDate.plus(
       maxTotalInvestment.minus(investmentAtStartDate)
     );
 
-    const grossPerformancePercentage =
+    let grossPerformancePercentage: Big;
-      PortfolioCalculator.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_MAX_INVESTMENT ||
+
-      averagePriceAtStartDate.eq(0) ||
+    if (
-      averagePriceAtEndDate.eq(0) ||
+      PortfolioCalculator.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_TIME_WEIGHTED_INVESTMENT
-      orders[indexOfStartOrder].unitPrice.eq(0)
+    ) {
-        ? maxInvestmentBetweenStartAndEndDate.gt(0)
+      grossPerformancePercentage =
-          ? totalGrossPerformance.div(maxInvestmentBetweenStartAndEndDate)
+        timeWeightedAverageInvestmentBetweenStartAndEndDate.gt(0)
-          : new Big(0)
+          ? totalGrossPerformance.div(
-        : // This formula has the issue that buying more units with a price
+              timeWeightedAverageInvestmentBetweenStartAndEndDate
-          // lower than the average buying price results in a positive
-          // performance even if the market price stays constant
-          unitPriceAtEndDate
-            .div(averagePriceAtEndDate)
-            .div(
-              orders[indexOfStartOrder].unitPrice.div(averagePriceAtStartDate)
             )
-            .minus(1);
+          : new Big(0);
+    } else {
+      grossPerformancePercentage =
+        averagePriceAtStartDate.eq(0) ||
+        averagePriceAtEndDate.eq(0) ||
+        orders[indexOfStartOrder].unitPrice.eq(0)
+          ? maxInvestmentBetweenStartAndEndDate.gt(0)
+            ? totalGrossPerformance.div(maxInvestmentBetweenStartAndEndDate)
+            : new Big(0)
+          : // This formula has the issue that buying more units with a price
+            // lower than the average buying price results in a positive
+            // performance even if the market price stays constant
+            unitPriceAtEndDate
+              .div(averagePriceAtEndDate)
+              .div(
+                orders[indexOfStartOrder].unitPrice.div(averagePriceAtStartDate)
+              )
+              .minus(1);
+    }
 
     const feesPerUnit = totalUnits.gt(0)
       ? fees.minus(feesAtStartDate).div(totalUnits)
       : new Big(0);
 
-    const netPerformancePercentage =
+    let netPerformancePercentage: Big;
-      PortfolioCalculator.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_MAX_INVESTMENT ||
+
-      averagePriceAtStartDate.eq(0) ||
+    if (
-      averagePriceAtEndDate.eq(0) ||
+      PortfolioCalculator.CALCULATE_PERCENTAGE_PERFORMANCE_WITH_TIME_WEIGHTED_INVESTMENT
-      orders[indexOfStartOrder].unitPrice.eq(0)
+    ) {
-        ? maxInvestmentBetweenStartAndEndDate.gt(0)
+      netPerformancePercentage =
-          ? totalNetPerformance.div(maxInvestmentBetweenStartAndEndDate)
+        timeWeightedAverageInvestmentBetweenStartAndEndDate.gt(0)
-          : new Big(0)
+          ? totalNetPerformance.div(
-        : // This formula has the issue that buying more units with a price
+              timeWeightedAverageInvestmentBetweenStartAndEndDate
-          // lower than the average buying price results in a positive
-          // performance even if the market price stays constant
-          unitPriceAtEndDate
-            .minus(feesPerUnit)
-            .div(averagePriceAtEndDate)
-            .div(
-              orders[indexOfStartOrder].unitPrice.div(averagePriceAtStartDate)
             )
-            .minus(1);
+          : new Big(0);
+    } else {
+      netPerformancePercentage =
+        averagePriceAtStartDate.eq(0) ||
+        averagePriceAtEndDate.eq(0) ||
+        orders[indexOfStartOrder].unitPrice.eq(0)
+          ? maxInvestmentBetweenStartAndEndDate.gt(0)
+            ? totalNetPerformance.div(maxInvestmentBetweenStartAndEndDate)
+            : new Big(0)
+          : // This formula has the issue that buying more units with a price
+            // lower than the average buying price results in a positive
+            // performance even if the market price stays constant
+            unitPriceAtEndDate
+              .minus(feesPerUnit)
+              .div(averagePriceAtEndDate)
+              .div(
+                orders[indexOfStartOrder].unitPrice.div(averagePriceAtStartDate)
+              )
+              .minus(1);
+    }
 
     if (PortfolioCalculator.ENABLE_LOGGING) {
       console.log(
@@ -1330,6 +1393,9 @@ export class PortfolioCalculator {
           2
         )} -> ${averagePriceAtEndDate.toFixed(2)}
         Total investment: ${totalInvestment.toFixed(2)}
+        Time weighted investment: ${timeWeightedAverageInvestmentBetweenStartAndEndDate.toFixed(
+          2
+        )}
         Max. total investment: ${maxTotalInvestment.toFixed(2)}
         Gross performance: ${totalGrossPerformance.toFixed(
           2
@@ -1349,9 +1415,12 @@ export class PortfolioCalculator {
       maxInvestmentValues,
       netPerformancePercentage,
       netPerformanceValues,
+      timeWeightedInvestmentValues,
       grossPerformance: totalGrossPerformance,
       hasErrors: totalUnits.gt(0) && (!initialValue || !unitPriceAtEndDate),
-      netPerformance: totalNetPerformance
+      netPerformance: totalNetPerformance,
+      timeWeightedInvestment:
+        timeWeightedAverageInvestmentBetweenStartAndEndDate
     };
   }
 

libs/common/src/lib/interfaces/timeline-position.interface.ts

@@ -16,5 +16,6 @@ export interface TimelinePosition {
   quantity: Big;
   symbol: string;
   tags?: Tag[];
+  timeWeightedInvestment: Big;
   transactionCount: number;
 }