Ebb & Flow

Based on the trickle of IPO filings at the end of the first quarter - only three total U.S. filings in February and March - there were rumblings that the window was nearly nailed shut. But in the past two weeks, four companies have thrown their hats into the ring, including a trio last week: Prestwick,Advanced Life Sciencesand SkinMedica.

Granted, filing is the easy part, as the backlog goes back 13 months (see "U.S. IPO Queue").But companies seem to be getting the message that a late-stage profile is the best way to have a shot at getting out. Of the three that filed last week, two have marketed products and one has a Phase III compound. ...