The share price wouldn't have dropped too much had Dr. Missling sold his shares. Maybe .50-.75 or so, and most likely those shares would have been absorbed quickly and the stock price would rebound back to around current levels.
Anavex is trading exactly where it should. It's a pre-revenue biotech with an exciting drug that may re-activate the Sigma-1 receptor. If there is indeed medicinal benefit from targeting Sigma-1, Anavex will be sitting pretty as the industry leader with a whole bunch of valuable patents. But until the FDA decides whether Sigma-1 is the future, the company shouldn't be worth more than a few hundred million dollars which is right around $5-$8/share.
Put another way: the recent Powerball $1B jackpot paid out around $300mm after taxes. If someone gave me the choice of the single winning ticket or 100% of the shares of Anavex, I'm taking the guaranteed $300mm every time. It's a lot of money and most P3 companies ultimately aren't worth hundreds of millions because their drugs fail. Fingers crossed Blarcamesine keeps on truckin'.