More than 5 million shares owned by China Aircraft Leasing Group's missing former chief executive Mike Poon have been sold since he resigned on June 17, exchange filings reveal. An option owned by Poon on 5.38 million shares at US$0.161 (HK$1.25) apiece - an almost 90 per cent discount to the market price - was exercised on June 19, the same day China Aircraft Leasing issued 5.4 million shares at that price "pursuant to exercise of share options under pre-IPO share option scheme other than by directors of the company" according to a notice the company filed with the stock exchange on Friday. Friedmann Pacific Asset Management, Poon's company - 10 per cent owned by his wife Christina Ng - through which he controls China Aircraft Leasing as the second-largest shareholder, exercised an option to 429,000 shares. It is unclear who gave instructions for the transaction, which occurred one day after Poon's job was taken over by China Aircraft Leasing chairman Chen Shuang following his abrupt resignation. Poon's whereabouts remain a mystery. China Aircraft Leasing had said Poon was on leave from May 18 amid reports he had disappeared, allegedly in relation to corruption investigations. The company said it had not been able to contact him after receiving his resignation letter on June 17 and appointed Chen to replace him the next day. Even though the stock's price plunged to HK$9.65, a three-month low, on June 19, Poon would have still netted HK$45 million if the shares were sold at market value. The stock has since rebounded to close at HK$10.38 yesterday. Poon has pre-IPO options to 1.3 million shares exercisable at the price of US$0.161 apiece before the end of this month through Friedmann Pacific, and another 15 million through a wholly-owned company, Equal Honour Holdings, according to China Aircraft Leasing's listing prospectus last June and according to its 2014 annual report. The shares had been sold off the exchange in cash to a party other than any substantial shareholders of the company, the filings indicate. Poon and Friedmann Pacific's interested share number in China Aircraft Leasing remained unchanged after exercising the option while his stake ratio dropped to 33.08 per cent from 33.72 per cent. "An unchanged share number with diluted shareholding ratio means new shares had been issued by the company and those shares had been sold to other parties," said David Yu, adjunct professor of finance at New York University in Shanghai. China Aircraft Leasing said in the same exchange filing that it had not repurchased any shares between June 11 and June 26. None of the substantial shareholders, with state-owned China Everbright Group being the largest with 42.91 per cent, had any disclosable changes in stake. China Aircraft did not respond to inquiries concerning the transaction or Poon's latest employment status and contact with the company. China Aircraft issued another 8 million shares at the price of US$0.161 on June 26 because a company controlled by a director exercised pre-IPO share options, according to the same notice. Apart from Poon's Equal Honour, Smart Vintage Investments owned by China Aircraft's vice president Winnie Liu Wanting is the only other company owned by a director entitled to pre-IPO share options in China Aircraft's listing prospectus.