The broad S&P 500 index fell 0.5 percent, the Dow Jones industrial average fell 0.9 percent, while the tech-heavy Nasdaq composite index closed down 0.4 percent.
This week, important statistics will be released that provide signals about how the American economy is doing, and there is nervousness ahead of the reports.
The cryptocurrency bitcoin fell sharply and was around $85,500 at 10 p.m.
During the day, it was announced that chip giant Nvidia is buying semiconductor company Synopsys for two billion dollars (equivalent to 19 billion kronor). Nvidia initially lost when the stock market opened, but then rose and closed 1.7 percent higher. Synopsys increased 4.9 percent.
Vaccine maker Moderna fell 7.0 percent after a document from the US FDA was leaked. The document talks about new restrictions on vaccines coming to market. Other vaccine makers also fell, including Novavax, which lost 5.1 percent.
