For example, see Yahoo's summary of insider and institutional activity.
Over the past quarter, insider share sales outweighed insider purchases by a factor greater than 1,000.
The result of this activity was that the number of shares held by insiders decreased by nearly 5%.
As for institutional investors, much the same trend held true. Institutional holdings of MSFT shares decreased by about 4.6%
Well, if you are considering buying MSFT, you might want to take into account that insiders and institutions have been selling at a rate which, if continued, would leave them almost entirely divested in five years. Perhaps they know something that you don't know.