# Issue

**Title:** Incorrect Mutual Fund Profit/Return Calculation

## Description
When calculating the profit or return for Mutual Funds, the reported figures are inaccurate. The system currently calculates these values based on the position, which leads to incorrect financial outcomes. The expected behavior is for Mutual Fund profit/return to be accurately determined using the value-cost identity.

## Task

Modify the repository so that the issue described above is resolved. The task's test suite verifies your patch by applying it on top of the base commit `ea95d2eee7e1` and running the modified tests.