Some institution (mutual fund, etc.) decides the recent run to $7.42 is good enough and wants out. But you can't just drop 1.2 million shares on the market. So you get your broker to sell gradually for his own account, over a few days or even weeks, putting constant downward pressure on the stock, but not creating a panic. Once the shares have been dribbled into the market, the broker crosses the 1.2 million from the client institution to his (company's) account and the deal's done. No big buyer, just a big seller and an orderly sale.

The upside is, the constant selling should subside. Since that appears not to be the case, there may be more.