The problem with Warburg is that what they did with Allos Theraputics has lead to many investors not getting ROI and a class action lawsuit has been filed. The deal they struck with Spectrum to purchase Allos suited Warburg fine, but to many stockholders, it was a bad deal. It is alleged that Warburg significantly undervalued Allos to get this deal done. http://www.classactioncentral.com/allos-therapeutics-inc-sued-for-unfair-practices-regarding-spectrum-merger/