Continued from page 1

Lefkowitz disagreed. The Supreme Court was never considering whether to strike down the provision affecting employers, but only the mandate requiring individuals to buy insurance. So businesses should have already been expecting to take on the extra costs, he said. (However, if the Supreme Court had rejected the individual mandate, that could have eventually led to getting rid of the employer mandate as well.)

Paul Zemsky, head of asset allocation at ING Investment Management in New York, thought the Supreme Court ruling was affecting the market, but indirectly. The ruling, he said, crystallizes the federal government’s polarization ahead of the election.

Republicans, who will feel ripped off, and Democrats, who will feel vindicated, are now less likely to agree on how to solve looming complications like tax increases and spending cuts that are supposed to take effect in January. “This doesn’t make me feel like the spirit of compromise will be in the air,” Zemsky said.

Though health care stocks fell overall, the companies had disparate reactions to the ruling. Insurers WellPoint and Aetna fell. Hospitals such as HCA Holdings and Community Health Systems rose.

When all of the new health care requirements kick in, insurers will have more customers, but they’ll also be subject to more taxes and regulations. They’ll also have to take on less-profitable customers, such as patients who are already sick.

But hospital emergency rooms, which have to treat patients regardless of whether they’re insured, are more likely to get paid if almost everyone they treat has insurance. Having insurance will also spur more people who might have otherwise put it off to seek medical treatment.

“Insured people have more purchasing power, and they’ll buy whatever you make, whether you’re a supplier of drugs or devices,” said Gerard Wedig, a health care economist at the University of Rochester.

U.S.-listed shares of Barclays, the British bank, plunged 12 percent. A day earlier, the bank had agreed to settle charges with U.S. and U.K. regulators who accused it of manipulating key international interest rates.

New York-based bank JPMorgan Chase fell 2.5 percent, more than any other company in the Dow index, after the New York Times reported that a trading loss there first estimated at $2 billion could eventually reach $9 billion.