The fact is, that most of those shares are already spoken for. Jeffries was obviously the one shorting the stock to hold it at 21 after earnings and at 20 after the announcement of the secondary. They will replace the shares they borrowed with their 18.25 shares - a very profitable transaction. And I expect that they will hold onto the rest of their shares and wait for higher prices.
analininspection, you are missing the point. The only one who got the shares @ 18.25 was Jeffries. On the day when the very strong earnings were announced and it was headed for 23, they shorted the stock at 21 to an enthusiastic audience of buyers, which locked in a large chunk of profits ... although it held the price down. Two days later, they shorted a lot more at 20, ahead of the announcement of the secondary. So, even though Jeffries didn't have the shares in hand until today, they had effectively sold off all the shares they wanted to sell beforehand. So about 10% of the float was thrown into the market and the price still went up. This is going much higher.