1. A lot of directors sell shares to finance something, for personal reasons, not because they think the share price is going down.
2. When a lot of directors sell or buy at once it is not necessarily a strong statement about the share price. It is often because they have what are called blackout periods when they cannot sell; before results would be an obvious one. Most directors only get a few windows during the year when they are allowed to buy or sell.
3. When directors buy, it is rarely an on market purchase. Most of the time directors are getting issued shares in lieu of a performance bonus, a dividend reinvestment plan, a share issue, an off-market transfer, a movement from one entity to another, a share purchase plan, as a bonus or through the maturing of options. What you want to look for are director transactions that are "on-market" transactions, bought with cash, and if they only buy a small amount, don't dismiss it – it often means more when a poor director buys shares; it is more significant than a rich director topping up.
