Then there's AMN Healthcare Services ( AHS), a $600 million company that's a one-stop shop for all of the staffing needs for hospitals -- a terrific story that should get better with age as we go into Obamacare and more and more people become elderly because of the nation's changing demographics. This is a terrific little company that's the largest in its industry with a very bright CEO, Susan Salka, and an even brighter future. Many businesses will be challenged by Obamacare, but hospitals are not one of them -- and when they need doctors or nurses and don't want to put them on full staff, they will call AMN Healthcare. I found myself wondering why this stock's market capitalization is only at $600 million, as this company's total addressable market is huge and it's recognized as best in class in the industry. But then I thought about it and recognized that, with a tougher market, no big mutual fund is going to want to get trapped in a junior growth stock with no place to go if things go wrong. Stocks like AMN are magic-carpet rides until they become roach motels when the tape morphs from glorious to toxic. Salesforce.com, a cloud play; Radian, a housing play; and AMN, a healthcare play: These stocks were all perfect just a few weeks ago. Now they're facing challenges as the buyers reassess their commitments and sellers ring the register. At the time of publication, Action Alerts PLUS, which Cramer co-manages as a charitable trust, had no positions in the stocks mentioned.