The securities watchdog will boost monitoring of health-care stocks for possible insider trading after increasing leaks of information that has the power to move markets, according to the top official of the Securities and Exchange Surveillance Commission.

The SESC will step up scrutiny of trading in pharmaceutical and biotechnology shares when those firms release data such as drug trial results, much as it does when companies announce takeover bids, share buybacks or earnings, Secretary-General Kiyotaka Sasaki said in an interview in Tokyo.

Sasaki is seeking to ensure fairness as more health care startups are going public, attracting investors keen to bet on their development of new treatments. The shares often move sharply upon reported success.