Quantitative finance (or "quant finance") is where math meets markets. Quants use advanced mathematics, statistics, and computer science to model financial markets, price derivatives, manage risk, and build algorithmic trading strategies.
Key tools: stochastic calculus, Monte Carlo simulations, machine learning, time series analysis, and partial differential equations. The Black-Scholes model (which won the Nobel Prize in 1997) is a classic quant model used to price options. Modern quants use Python, R, C++, and massive computing power.
Top quant firms like Renaissance Technologies, Two Sigma, and DE Shaw generate billions in profits using mathematical models. Jim Simons' Medallion Fund at Renaissance returned 66% annually before fees for over 30 years — arguably the greatest investment track record in history. Quant roles are among the highest-paying in finance.