TYK Medicines (HKG:2410) said Chairman and Chief Executive Officer Wu Yusheng has recently purchased company shares on the open market and may make further purchases depending on market conditions.

The total increase in his shareholding is currently expected not to exceed HK$2 million, according to a Hong Kong bourse filing.

Wu will fund the purchases with his own funds and has undertaken to voluntarily lock up the shares acquired over the next month for six months from their respective purchase dates.

Shares of the firm were down nearly 10% in Wednesday morning trade.