A former director of Kingboard Chemical Holdings has cashed in $423 million after selling a 2.5 per cent stake, or 18 million shares, in the company, according to sale arranger ABN Amro Rothschild. The sale occurred hours after the maker of laminates, copper foil and printed circuit boards said its net profit last year more than doubled on Wednesday. The shares were sold at $23.50 each, a 3.9 per cent discount to Wednesday's closing share price of $24.45. The shares were part of a pool owned by Kingboard directors but held through Hallgain Management. The director is no longer associated with the firm and holds no more Kingboard shares through Hallgain.