The latest on developments in financial markets (all times local):
The Dow Jones Industrial Average plunged 500 points, its second straight drop of that size and its fourth big decline this month.
Longtime market favorites like Microsoft and Amazon took heavy losses Monday. Health care companies also fell sharply.
A measure of small-company stocks fell into a bear market, a decline of 20 percent below their recent peak.
The market is now well into the red for the year and the S&P 500 index is trading at its lowest level since October 2017.
The S&P 500 fell 54 points, or 2.1 percent, to 2,545.
The Dow lost 507 points, or 2.1 percent, to 23,592. The Nasdaq composite lost 156 points, or 2.3 percent, to 6,753.
Bond price rose, sending yields lower.
Stocks are mostly lower in midday trading on Wall Street, though they've steadied after a rocky start.
Health insurers and hospitals are falling Monday after a judge in Texas ruled that the 2010 Affordable Care Act is unconstitutional.
HCA, the largest publicly traded hospital operator, fell 2.4 percent and Centene, an insurer, lost 5.4 percent.
Retailers are also sinking, but banks are rising.
The S&P 500 index fell 8 points, or 0.3 percent, to 2,591. After several weeks of declines the benchmark index is trading near its lowest level of the year.
The Dow Jones Industrial Average lost 84 points, or 0.9 percent, to 24,024. The Nasdaq composite slipped 8 points, or 0.1 percent, to 6,902.
Bond prices rose. The yield on the 10-year Treasury fell to 2.87 percent.
Health care stocks are leading major U.S. indexes lower in early trading on Wall Street after a federal judge ruled that the 2010 Affordable Care Act is unconstitutional.
Hospital operators and insurers that would stand to lose if the law is weakened or overturned took some of the biggest losses early Monday.
HCA, the largest publicly traded hospital operator, fell 3.8 percent and Centene, an insurer, lost 8.8 percent.
The S&P 500 index fell 21 points, or 0.8 percent, to 2,578. After several weeks of declines the benchmark index is trading at its lowest level of the year.
The Dow Jones Industrial Average lost 208 points, or 0.9 percent, to 23,893. The Nasdaq composite fell 56 points, or 0.8 percent, to 6,853.