It would appear it's only illegal for people like us. We all see manipulation and funny trading examples every day. You have people who make their livings following unusually high volumes and jumping on the trend. Sure enough, mysteriously. those high volume moves are generally followed by announcements of something big within a day or two.
Think you're being a little naïve believing it doesn't happen here. How then would you explain the trading yesterday morning. Did someone wake up with a hankering to buy a million at a premium and sell it at a loss a little later. Maybe needing a tax loss?