The Patient Protection and Affordable Care Act, the President’s health care initiative, set out new mandates, subsidies and credits to employers and individuals to increase Americans’ access to health care. Upon its passage in March 2010, investors began boosting the shares of drug makers, insurance providers and hospitals because they all suddenly had a lot more paying customers, courtesy of the government and taxpayers.

Shares of Pfizer PFE -2.34% , for example, had fallen 50% during the eight years of the Bush Administration, January 2001 to January 2009. In contrast, its shares are up 70% during the Obama Administration, almost in a straight line. Sixty-four percent of the gains in the maker of Viagra, Zoloft and Lipitor have come since ACA passed.

Insurance provider Unitedhealth Group UNH -4.94% is up 73% since Obamacare passed. Smaller biotechs have gained a lot more, led by Alexion Pharmaceuticals ALXN -3.57% , up 252%.

Overall, SPDR Health Care XLV -2.26% , which includes all the health care stocks in the S&P 500, is up 31% since the President’s health-care law passed, vs. 27% for the broad market. It’s still a good bet going forward, as most of the benefits still lie ahead.