The effect of board structure on firm value: A multiple identification strategies approach using Korean data

Outside directors and audit committees are widely considered to be central elements of good corporate governance. We use a 1999 Korean law as an exogenous shock to assess whether and how board structure affects firm market value. The law mandates 50% outside directors and an audit committee for large public firms, but not smaller firms. We study this shock using event study, difference-in-differences, and instrumental variable methods, within an overall regression discontinuity approach. The legal shock produces economically large share price increases for large firms, relative to mid-sized firms; their share prices jump in 1999 when the reforms are announced.

► Korea's 1999 board reforms predict higher firm market value.
► We find evidence of a causal effect using multiple causal inference strategies.
► Both 50% outside directors and audit committees predict higher value.