Technology companies led U.S. stocks broadly higher Monday, extending the market’s recent rally. Trading was muted following the Christmas holiday as Wall Street kicked off the final week in a banner year for the stock market.

Trading is expected to be quiet, but potentially volatile, this week as the omicron coronavirus variant continues to spread quickly throughout the U.S. and overseas. However most big investors have closed out their positions for 2021, and are like to hold their ground until next week.

The S&P 500 was up 1.1% as of 1:49 p.m. Eastern. The benchmark index, which capped a holiday shortened week Thursday with an all-time high, is on pace to close out the year with a 27.3% gain. The Dow Jones Industrial Average rose 0.7% and the technology-heavy Nasdaq rose 1.2%.

The major indexes posted weekly gains last week as fears ebbed about the potential impact of omicron outbreaks. However, much is still uncertain about the variant, which is spreading extremely quickly, leading to a return to pandemic restrictions in some places.

Technology companies led the gains. Nvidia climbed 3.9%, while Apple and Microsoft each rose 1.9%.

The price of U.S. crude oil rose 2.7%, continuing its climb higher this month. Energy companies like Devon Energy and Diamondback Energy were among the biggest gainers in the S&P 500.

Hundreds of flights were cancelled in the U.S. over the holiday weekend, with airlines reporting COVID-related staffing problems. France reported more than 100,000 new cases in a daily record.

Airline stocks were down on the news, with Delta Air Lines and United Airlines falling roughly 1%.

Shares in cruise line operators also fell. Norwegian Cruise Line slid 2.7% for the biggest drop in the S&P 500. Carnival and Royal Caribbean slipped more than 1%.

Authorities in many countries have doubled down on vaccination efforts as omicron outbreaks complicate efforts stave off fresh lockdowns while hospitals are still under strain from delta variant infections.

Bond yields were mixed. The yield on the 10-year Treasury slipped to 1.48% from 1.49% on Thursday.

Asian and European markets were either closed or mostly higher on Monday. London and Hong Kong were closed, while Japan’s stock market closed slightly higher.

In other international developments, the Turkish lira fell another 5% against the dollar. The currency has tumbled sharply this year as the Turkish government has tried to invigorate 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 prop up the currency.