Shares were slightly higher on Monday in muted trading after the Christmas holidays, aided by big tech companies like Apple and Nvidia.
Trading is expected to be calm, but potentially volatile, this week, as the omicron coronavirus variant continues to spread rapidly in the United States and abroad. However, most of the big investors have closed their positions for 2021 and are expected to hold on until next week.
The S&P 500 Index was up 0.9% at 11:00 a.m. Eastern time. The Dow Jones Industrial Average rose 0.6% and the tech-rich Nasdaq rose 1.1%.
The S&P is on track to end the year up nearly 27%, a record year for the stock market.
Last week, the S&P 500 set a new record as fears faded over the potential impact of omicron outbreaks. However, much is still unclear about the variant, which is spreading extremely quickly, leading to a return to pandemic restrictions in some locations.
Hundreds of flights were canceled in the United States over the holiday weekend, with airlines reporting staff issues related to COVID. France has reported more than 100,000 new cases in a daily record.
Airlines shares were lower on the news, with Delta Air Lines, United Airlines and American Airlines all falling more than 2% in early trading.
Authorities in many countries have doubled their vaccination efforts as omicron outbreaks complicate efforts to avoid further closures while hospitals remain under pressure from delta-variant infections.
Asian and European markets were either closed or mostly up on Monday. London and Hong Kong were closed, while the Japanese stock market closed slightly higher.
In other international developments, the Turkish lira fell another 5% against the dollar. The currency has fallen sharply this year as the Turkish government tried to reinvigorate its economy despite chronically high inflation. The government announced a plan last week that would encourage Turks to put their money back into lira bank accounts to support the currency.