Robert Engle

ARCH (Autoregressive Conditional Heteroskedasticity), developed by Robert Engle in 1982, is a statistical model that captures how volatility in financial time series changes over time and tends to cluster. The model shows that periods of high volatility are typically followed by more high volatility, and periods of calm tend to persist.

Engle shared the 2003 Nobel Memorial Prize in Economic Sciences with Clive Granger for developing methods to analyze economic time series. Engle was specifically cited for creating the ARCH model, which became essential for measuring and forecasting volatility in financial markets.

GARCH (Generalized ARCH) extends Engle's original model by allowing current volatility to depend on both past squared returns and past volatility. The GARCH model is widely used by financial institutions to estimate Value-at-Risk, price derivatives, and calculate capital requirements under regulations like Basel III.

Engle's volatility models allow financial institutions to dynamically estimate and forecast market risk, which is essential for portfolio optimization, derivative pricing, and regulatory compliance. His methods are used by banks, hedge funds, and risk managers worldwide to measure exposure to changing market conditions.