Georgetown professor Ken Homa has a good analysis of the health care industry cost structure, and takes issue with Obama's recent targeting of HMO profits. Homa's analysis is correct but could be easier to understand with a simple graphic, which I've done here.
Conclusion: Killing HMOs isn't going to save our health care system.
HMO Profits constitute 2% of total US health care costs
Of course, I've written about health care costs before as well.