Large Korean firms subject to a new mandate requiring 50% of board members being outside directors saw share prices rise by an average of 15% relative to mid-size firms unaffected by the mandate.

"The estimated effects are economically important. In our event study, large firms’ share prices rise by an average of 15% relative to mid-sized firms over a broad window covering our principal events. Our DiD results suggest a roughly 0.13 increase in ln(Tobin’s q) from June 1, 1999 through the end of 1999 (this period captures the full legislative process).