Blue chips in New York rose Tuesday, as enthusiasm about the economic reopening lifted travel and energy stocks.
The Dow Jones Industrials maintained gains of 129.27 points by lunch hour to 34,658.72.
The S&P 500 added 3.45 points to 4,207.50, as weakness in technology stocks offset gains made in energy, materials and financials.
The NASDAQ dipped 21.03 points to 13,727.71, as technology stocks underperformed the broader market.
Markets in the U.S. were shuttered Monday for Memorial Day.
The gains came as COVID cases continue to decline and vaccinations rise in the U.S. In a major milestone, more than half the U.S. population has received at least one dose of a COVID vaccination, according to data posted by the Centers for Disease Control and Prevention.
The improving domestic coronavirus situation, coupled with the arrival of summertime weather, sparked another day of strong gains in Wall Street's reopening trades like travel and hospitality.
American Airlines and United Airlines each gained 2% after the Transportation Security Administration said it screened an average of 1.78 million people from Friday through Monday, well above the volumes one year ago and another sign that U.S. air travel has reached a pandemic-era high.
Those volumes are more than six times higher than a year ago but still 22% below Memorial Day weekend in 2019.
Meanwhile, aircraft maker Boeing gained 2.2%, after one analyst recommended investors discount near-term hurdles for the Dow component and buy the stock while it's still below where it traded in early 2020.
Shares of cruise-operators Carnival Corp. and Norwegian Cruise Line Holdings, two other reopening bellwethers, jumped more than 2% apiece.
Energy stocks gained as U.S. oil futures jumped. Exxon, Chevron and Marathon Petroleum all rose.
Meme stock AMC Entertainment was jumping again after selling $230.5 million in new stock to an investor. The shares were up 12% after doubling last week.
Zoom Video Communications and Hewlett Packard Enterprise are set to report quarterly earnings results on Tuesday after the bell.
The Dow collected 1.9% and the S&P 500 gained 0.6% in May, to mark their fourth consecutive positive month.
The NASDAQ gained 2.1% last week to post its best weekly performance since April. However, the tech-heavy composite lost 1.53% in May, breaking a six-month win streak.
Prices for 10-Year Treasurys dropped, raising yields to 1.63% from Friday's 1.58%. Treasury prices and yields move in opposite directions.
Oil prices collected $1.38 to $67.70 U.S. a barrel.
Gold prices staggered $4.10 to $1,901.20 U.S. an ounce.