Internal Rate of Return (IRR) is the annualized, time-weighted return that sets the net present value of a deal's cash flows to zero. It is the headline return metric for both individual deals and funds, and the figure most LBO modeling tests ask you to solve for. Because it is time-sensitive, IRR rewards returning capital quickly: a dollar back in year two is worth far more to the IRR than the same dollar in year six.
Why it matters
IRR is the number most PE firms and their LPs lead with. It compounds, it is time-aware, and it captures the value of pulling cash forward, which is why moves like a dividend recapitalization can lift IRR even when they do not change the total dollars returned. That same sensitivity is why IRR has to be read with a second metric beside it.
The same multiple, two different IRRs
Roughly speaking, a 3.0x MOIC earned over five years is about a 25% IRR. Hold that same 3.0x for seven years and the IRR falls to about 17%. Same money returned, very different IRR, entirely because of time. This is why holding period is a direct lever on the headline return.
The common mistake
Reading IRR without its MOIC. A high IRR can come from a quick, small win or from financial engineering like an early recap, while a lower IRR on a larger MOIC may return far more dollars. The two metrics have to be read together: IRR for speed, MOIC for magnitude. At the fund level, the same logic extends to DPI, the cash that has actually been returned to LPs.