Monte Carlo Simulation
Monte Carlo simulation samples repeatedly from a specified model to explore possible outcomes and their dispersion. It can help examine uncertainty, but its results depend on the model, inputs, and assumptions.
THE IDEA
Making History
In the early 1990s, like many of my friends in quantitative finance, I became addicted to the various Monte Carlo engines, which I taught myself to build, thrilled to feel that I was generating history, a Demiurgus. It can be electrifying to generate virtual histories and watch the dispersion between the various results. Such dispersion is indicative of the degree of resistance to randomness. This is where I am convinced that I have been extremely lucky in my choice of career: One of the attractive aspects of my profession as a quantitative option trader is that I have close to 95% of my day free to think, read, and research (or “reflect” in the gym, on ski slopes, or, more effectively, on a park bench). I also had the privilege of frequently “working” from my well-equipped attic.
The dividend of the computer revolution to us did not come in the flooding of self-perpetuating e-mail messages and access to chat rooms; it was in the sudden availability of fast processors capable of generating a million sample paths per minute. Recall that I never considered myself better than an unenthusiastic equation solver and was rarely capable of prowess in the matter—being better at setting up equations than solving them. Suddenly, my engine allowed me to solve with minimal effort the most intractable of equations. Few solutions became out of reach.
When to use it
Pricing complex financial derivatives where closed-form solutions are unavailable.
Evaluating project risks by simulating time and cost estimates under uncertainty.
Modeling the spread of infectious diseases to inform public health interventions.
Optimizing supply chain logistics by simulating demand, lead times, and other variables.
FROM THEORY TO EVERYDAY LIFE
In practice
Option Pricing
To price an option with Monte Carlo simulation, generate paths under an appropriate pricing model, calculate each payoff, and estimate its discounted expected value. The result depends on the model and its assumptions.
Project Risk Analysis
Managers use Monte Carlo simulation to assess the likelihood of completing a project on time and within budget by modeling uncertainties in task durations and costs.
A MOMENT TO REFLECT
Put it to work.
How can Monte Carlo simulation help you assess the risk of a financial portfolio?
In what non-financial domains could you use Monte Carlo methods to explore uncertainty?
What are the potential pitfalls of relying on Monte Carlo simulation without understanding underlying assumptions?
CONTINUE THE CONVERSATION
Source texts
- Fooled by Randomness The Hidden Role of Chance in the Markets and in Life (Nassim Nicholas Taleb)