Excel Function : XIRR
Returns the internal rate of return for a schedule of cash flows that is not necessarily periodic
Microsoft Excel Reference Page
Syntax and Description of the XIRR Excel Function
The syntax for the XIRR function in Microsoft Excel is: XIRR(values, dates, [guess]) Values is a required array or reference to the cells that contain the numbers for which you want to calculate the internal rate of return. Dates is a required array or reference to the cells that contain the date or time values for which the corresponding values are paid. Guess is an optional number that you guess is close to the result of XIRR.
About XIRR Excel Function
XIRR is an Excel function that returns the internal rate of return for a given investment. The internal rate of return is the interest rate that makes the present value of the investment's cash flows equal to the investment's initial cost.