Advanced Finance

Monte Carlo for Business Decisions

Stop asking what a project is worth and start asking what the distribution of what it is worth looks like. The technique is ninety minutes of work; knowing where it lies to you is the expertise.

  • Advanced
  • 8 min total
  • 12 chapters

What decision this helps you make: Whether to commit capital to a project whose value depends on several uncertain inputs at once — and how much of the resulting risk is worth paying to reduce.

What this topic is

Monte Carlo simulation replaces each uncertain input in a model with a probability distribution, samples thousands of complete scenarios, and reports the distribution of the output. The answer is not a number; it is a shape, and the shape is what you are buying.

Why it matters

Business models are full of caps, floors, thresholds, and options — all of which make them nonlinear. Running a nonlinear model at average inputs produces an answer that is not merely imprecise but systematically wrong, and the direction of the error is predictable once you know what to look for.

Who should learn it

Anyone who builds or reviews capital models: corporate development, FP&A, project finance, private equity, and operators making irreversible commitments under genuine uncertainty.

What you will understand

  • Why a model run at average inputs gives the wrong answer, with the arithmetic
  • How to choose distributions, and why correlation matters more than any of them
  • What to read off the output beyond the mean
  • The two ways simulations most often mislead: fabricated inputs and double-counted risk

Prerequisites

Common misconception

"Monte Carlo makes the forecast more accurate." It does not improve a single input. What it does is stop you averaging inputs before pushing them through a nonlinear model, and it makes the shape of the downside visible. A hundred thousand trials on invented distributions produces a beautifully smooth answer that is exactly as wrong as the assumptions underneath it — with a spurious authority the spreadsheet never had.