diff --git a/apps/api/src/app/portfolio/portfolio.service.ts b/apps/api/src/app/portfolio/portfolio.service.ts
index 2b829722c..e6d87db1c 100644
--- a/apps/api/src/app/portfolio/portfolio.service.ts
+++ b/apps/api/src/app/portfolio/portfolio.service.ts
@@ -206,7 +206,7 @@ export class PortfolioService {
       .filter((timelineItem) => timelineItem !== null)
       .map((timelineItem) => ({
         date: timelineItem.date,
-        value: timelineItem.grossPerformance,
+        value: timelineItem.grossPerformance.toNumber(),
         marketPrice: timelineItem.value
       }));
   }