Clients of investment banks in an IPO have a choice to invest or pass on the deal. There are many things they consider when making this decision, and the price of the deal is one of those. Assuming they are not given inaccurate information, they are not getting "bilked" by the banks if the stock goes down in the aftermarket. The clients know this is a possibility, and they chose to invest at $38 per share. Right now those shares are worth less than the offer price, which is disappointing to the clients, but they made the decision to invest at $38 per share.