03. Cumulative Returns

PRDTM2-786 AI Trading C3 L1 3 Cumulative Returns V4

Understanding Arithmetic Returns

Concept of Arithmetic Returns

  • Measure of investment performance.
  • Calculated as (ending value - beginning value) / beginning value.

Limitations

  • Not suitable for multi-period analysis.
  • Returns do not simply add up over time.

Example

  1. Starting Investment: $10 million.

  2. First Year Result:

    • Ending value: $11 million.
    • Arithmetic Return: 10%.
  3. Second Year Result:

    • Ending value: $9.9 million.
    • Arithmetic Return: -10%.

Misinterpretation of Returns

  • Adding 10% and -10% yields a return of 0%, which is incorrect.
  • Each year's return is based on its preceding year's ending value.

Conclusion

  • Correct calculation reflects a negative return of 1% over two years, highlighting the need for proper calculations beyond simple arithmetic addition.

Which of the following statements correctly reflects the limitations of arithmetic returns when calculating performance over multiple time periods?

SOLUTION:
  • Arithmetic returns are not time-additive, meaning simple addition does not provide an accurate measure of total return over multiple periods.
  • The total return over multiple periods should be calculated by multiplying the returns for each period, not by adding them.