Huntsville, AL – The chairman and chief executive officer of Adtran Incorporated has sold nearly 274 million dollars worth of shares in the telecommunications equipment company. Adtran officials say Mark Smith sold the stock to diversify his personal financial portfolio. That's the same reason given when Smith sold a similar number of shares for 168 million dollars last May. Adtran says there has been no change in Smith's role as chairman and chief executive of the Huntsville-based company. He still owns nearly four million Adtran shares worth about 520 million dollars. During the past 12 months, Adtran stock has increased about 141 percent. Share prices dropped about nine percent Wednesday, closing at 65 dollars and five cents.