12 million shares were sold short into the market from a block position throughout the day. Those two t-trades were the cover “buys” from the client’s block at 98.5% of the VWAP for the sells earlier in the day. It is also know as a “net trade”. The 1.5% difference is the fee the broker charges.
Block trading is rarely used by retail given the high cost.
But is used by large holders...usually note holders when they are selling newly issued stock. It is the best way to mitigate the selling’s downward impact on the pps especially when volume is light.