Why have pivotal members of the Congress been reluctant to allow individuals the choice to buy into a public health insurance option? A political-economic reason is that the "bipartisan" group of six senators responds more to the interests of health insurance companies than public opinion, including the median voter. While this is hard to assess directly (although we do know they receive substantial campaign finance from insurance companies), we can however observe the effects of (a somewhat unanticipated) decision they made on those who stand to privately benefit from that decision.

Here is how the share prices of three major insurance companies (Cigna (NYSE: ), United Healthcare Group, Aetna (NYSE: )) responded on Tuesday, July 28 to the Monday night announcement that the group of six senators is going to eliminate the public option from their version of the health care reform legislation [graph produced using Yahoo Finance]. We have basically an 8-10 percent gain for these companies from the Senate announcement. And as the graph below shows, the S&P 500 index (yellow) was essentially flat.