Approximately HK$7.78 billion (US$998 million) worth of Ping An Insurance (Group) Co. of China Ltd.'s (2318.HK)(601318.SH) Hong Kong-listed shares were transferred before the market opened Wednesday, weighing on the insurer which was down 3.5% in the morning session.

A total of 120 million shares were transferred at HK$64.85 in two block trades before the market opened, according to stock exchange data. Ping An's shares closed at HK$64.85 Tuesday.

The insurer didn't place any shares, Ping An spokesman Richard Sheng said Wednesday, adding that he is unaware of any major shareholders reducing stakes.

"The share transfer could be related to some derivatives transaction of Ping An's shares," a person familiar with the matter said Wednesday, declining to comment further.

Ping An announced a deal March 14 to sell a 3.4% stake to a company controlled by Hong Kong's Cheng Yu-tung, a billionaire whose interests span real estate, infrastructure and jewelry retailing.