Barack Obama wanted to change American health-care as we know it. And he is, in ways that go far beyond the goals of the Affordable Care Act.

For weeks, headlines have cataloged the upheaval at private employers: UPS dropping coverage for employed spouses, IBM reworking retiree benefits. Yesterday came the biggest change: Walgreen Co., the largest U.S. drugstore chain, told 160,000 workers they must buy their insurance through a private exchange rather than having the company arrange their coverage.

None of the moves was dictated by the health-care law. All, though, have occurred in an environment shaped by Obamacare, which has pushed businesses and governments to re-examine their health-care role as costs soar and national priorities shift. The law now is giving businesses cover to loosen the decades-old link between jobs and health insurance, a shift that may further cloud the outlook for an already unpopular law.

Eoin Treacy's view The USA's Affordable Care Act tends to fuel emotional commentary on both sides of the political divide not least because of the scope of the changes it will usher in on October 1 st . What most people can agree on is that health insurers have been among the greatest beneficiaries to date. The law will supply them with millions of new customers and the justification to increase premiums on their existing customers. .

What struck me about the sector this morning is that while 435 of the S&P500's constituents posted a positive performance yesterday, almost all of the larger health insurers declined. United Healthcare, which is by far the largest company in the sector, had become quite overextended relative to the 200-day MA following a particularly impressive performance from the April low and posted a downside key day reversal yesterday. The potential for mean reversion has increased. WellPoint Inc. also pulled back sharply. Humana has at least paused in the region of the psychological $100 following an impressive rally. Cigna is equally susceptible to mean reversion and is working on a downside weekly key reversal. Aetna is also pulling back.

AON Plc. is mentioned in the above article and will manage some of the health exchanges set to open at the end of the month. The share is listed in the US and the pace of its advance has picked up this week. A break in the progression of higher reaction lows would be required to question the consistency of its steep medium-term advance.