Yesterday, the New York attorney general slapped UnitedHealth Group by announcing that it would sue the health plan for allegedly underpaying for services. Ordinarily, a company the size of UHG--the nation's largest health insurer--would set its legal department on the matter and turn executives' attention elsewhere. But in this case, given that the probe is also taking a hard look at how subsidiary Ingenix works with health plans nationwide, the AG's actions could have a meaningful effect on UHG's business, some observers say. Article