XIRR — Extended Internal Rate of Return
XIRR refers to a mathematical function used to determine the annualised rate of return for a series of cash flows that do not occur at regular intervals. It is the standard method for measuring the actual return on Systematic Investment Plans (SIPs) and other staggered investment strategies.
Why CAGR Is Insufficient for SIPs
CAGR is calculated between two data points — a beginning value and an ending value. When investments are made in multiple instalments at different points in time (as in a SIP), each instalment has a different investment horizon. XIRR accounts for the timing of every individual cash flow.
How XIRR Works
XIRR finds the discount rate that makes the Net Present Value (NPV) of all cash flows equal to zero. Each outflow (investment instalment) and inflow (redemption proceeds) is paired with a specific date. The function iteratively solves for the rate.
In spreadsheet tools, the syntax is: =XIRR(values, dates, guess)
Interpreting XIRR
The output is expressed as an annualised percentage rate. A SIP that generated an XIRR of 13% can be interpreted as having grown at a rate equivalent to 13% per annum, accounting for the timing and compounding of each instalment.
Limitations
- •XIRR assumes that interim returns are reinvested at the computed rate, which may not always hold true.
- •The function can produce multiple solutions in cases of unconventional cash flow patterns.
- •A higher XIRR over a short period may not be representative of long-term performance.
XIRR is considered the most accurate measure for evaluating the performance of SIPs, goal-based investments, and portfolios with staggered contributions or withdrawals.