AeroVironment Inc. Chairman Timothy Conver plans to sell a portion of his shares in the company, the Simi Valley drone maker announced Friday.

Under Securities and Exchange Commission rules, Conver may sell up to 600,000 shares over a 12-month period. After the sale, which will begin no earlier than January, Conver will retain almost 1.5 million AeroVironment shares, or a 5.9 percent stake in the company.

AeroVironment develops and manufactures unmanned surveillance aircraft and drone missiles for defense contractors such as Lockheed Martin Corp. as well branches of the U.S. military.

Conver served as the company's chief executive from 1992 until 2016.

Shares of AeroVironment (AVAV) closed Monday down $5.55, or 7.4 percent, at $69.86 on the Nasdaq.