Cumulative return is simply the compounding of each of your returns.
Assume you started with an investment of $1, and you had returns of 7%,
5.5%, -2.3% and 14.2%.
Your ending value would be:
=1.07*1.055*.977*1.142
And your cumulative return would be the above result less the $1 you started
with.
In formula terms, if you have returns of i1 to in, your cumulative return
is:
=(1+i1)*(1+i2)*...*(1+in)-1
Regards,
Fred.