The Dow Jones Industrial Average and S&P 500 opened lower on Thursday as markets continued to churn following big gains earlier in the week.
The 30-stock index slid 139.87 points to 29,257.76.
The S&P 500 fell 12.15 points to 3,560.51
The NASDAQ gained 41.99 points, to 11,828.42.
Airline and cruise-operator stocks fell broadly. United Airlines and Delta were down 1.5% each. American Airlines dipped 0.8% and Southwest pulled back by 2.6%. Norwegian Cruise Line and Carnival dipped more than 3% each and Royal Caribbean slipped 4%.
More positive news on the vaccine front could come soon, as Moderna announced on Wednesday evening that its phase-three trial had accrued enough cases of the coronavirus to submit the preliminary results to an independent safety monitoring board.
The positive news for vaccines comes amid a worrying rise in Covid-19 cases across the country. The United States has now confirmed more than 10 million cases of the virus and some areas, including New York City and San Francisco, have announced new economic restrictions in an attempt to slow the spread.
On the data front, the U.S. Labor Department reported initial weekly jobless claims fell last week to 709,000 from 757,000 in the prior week. That marked the fourth straight weekly decline for initial claims.
Prices for the 10-Year Treasury gained ground, lowering yields to 0.92% from Tuesday's 0.96%. The bond markets were closed Wednesday for Veteran's Day. Treasury prices and yields move in opposite directions.
Oil prices jumped 37 cents to $41.82 U.S. a barrel.
Gold prices improved $13.80 to $1,875.40