The Associated Press

Specialists Robert Canzani, left, and Henry Becker, second from right, work at their posts on the floor of the New York Stock Exchange Thursday, June 28, 2012. Stocks dropped sharply Thursday after the Supreme Court upheld the central provision of President Barack Obama's health care overhaul, a requirement that almost all Americans carry health insurance. (AP Photo/Richard Drew)

By DANIEL WAGNER AP Business Writer

WASHINGTON (AP) — Hospital stocks rose sharply Thursday after the Supreme Court guaranteed them millions more paying customers by upholding the core of President Barack Obama’s health care overhaul.

Some insurance company stocks fell in choppy trading as investors fretted about the costs of rules included in the law.

‘‘For the hospitals, it means that they get payment and they get more potential customers,’’ said JJ Kinahan, chief derivatives strategist for TD Ameritrade. Insurers ‘‘have to be less selective of their clients, which is bad for them,’’ he said.

The stock of Hospital Corp. of America, the largest private hospital chain in the United States, closed up 11 percent. Community Health Systems rose 8 percent, Health Management Associates 9 percent.

Quest Diagnostics, which runs laboratories, and Laboratory Corp. of America both gained about 3 percent.

The ruling will add 32 million Americans to the rolls of the insured, vastly expanding the pool of health care consumers, said Jeffrey Loo, a stock analyst with S&P Capital IQ, a research group.