It is called bot trading, automated trading or algorithmic trading.
Big brokers are not restricted to a minimum trade like us regular people. They buy or sell in small amounts to manipulate the current share price. They also buy or sell small amounts when either getting rid of stock or buying stock so it goes under the radar.
Happens regularly on stocks when you watch the course of trades.
Have a read of the forum on HC called algorithmic trading.
CCU Price at posting:
77.6¢ Sentiment: Buy Disclosure: Held