Adobe chairman John Warnock sold "over $6 million" in shares last month, according to the US Securities and Exchange Commission (SEC).

He sold 150,000 shares at $40.15 December 23. The Adobe chairman has sold over half a million company shares in the past year to the tune of $15 million, Reuters reports.

Warnock remains one of Adobe's largest shareholders and has also contributed $600,000 to Salon.