Definition: Cumulative Return
Cumulative Return is the total return since the first Account Balance entry, adjusted for deposits/withdrawals.
Today's Cumulative Return = (1 + Yesterday's Cumulative Return) * (1 + Today's Daily Return) - 1
For example: If your Cumulative Return yesterday was 10%, and today's Daily Return is 2%, today's Cumulative Return would be 12.2%.
Read about how Daily Return is calculated to understand how it smoothes the effect of deposits.