Automatic trading of institutional investors. They pay in monthly/yearly packages, not by the trade.
Not really a conspiracy in most instances but actually a benefit to the 'flow' of the market.
When larger holders or "instos" (institutional shareholders) want to sell at a particular range their bots go to work and drip feed to market over many weeks/months to eventually get their sale (or purchase). They're buying/selling numerous stocks all day every day.
The alternative is having situations where millions of shares get dumped on the sell side and causes a firesale.
The opposite is also true, if you saw 20Million shares drop on the buy side of TNG we'd be up 50% in the day on hype alone - and that buy package would never get filled.
TNG Price at posting:
9.0¢ Sentiment: Hold Disclosure: Held