Thanks to all the posters trying to help figure this out.
I feel as though something totally unexpected had to happen to cause this situation. I do not believe that the price or market reaction to the offering would qualify as unexpected since guiding management in these areas is one of the most important roles of an investment banker. Unless their banker is grossly incompetent, they should be able to peg the price of a secondary to within a very narrow range. Also, what the hell could the banker or management have learned about pricing between 4pm and 1am?
Another possibility is PQ was planning some kind of acquisition to take advantage of depressed prices in the sector and then discovered their target was out of reach, thus no need for dilutive funds.