This was a "Mezzanine" trade. Large institutions and shareholders trade by making offline agreements at prices, quantities and timing so as to not interfear with the market. It then is reported on the open market as a sale, though the retailers were never involved either at Bid or Ask prices. The same thing happened the day before.
All in all it is a good thing. It probably means that someone who purchased large quantities at ~$3.50C wanted to cash out a portion and there was someother institution or person who thought $10 US. was a good entry point for a ~1 million share position. Usually hedge funds or mutual funds.