(FILES) In this file photo a man passes the building before the opening bell at the New York Stock Exchange (NYSE) on May 26,…
FILE - A man passes the building before the opening bell at the New York Stock Exchange on Wall Street in New York City, May 26, 2020.

Wall Street opened the new month with modest gains Monday as investors express both optimism and caution over an economic revival.

The Dow Jones Industrial Average rose 91 points – up a fraction. The S&P 500 and Nasdaq were also up less than 1%, but Monday's close of 9,552 was the highest level for the Nasdaq since February. The S&P also closed at its highest level since March.

Travel-related stocks led Monday's gains with prices of shares in major cruise lines, hotels and airlines all higher.

But analysts are warning investors to be cautious and diversify their holdings, saying it is still to be seen what effects U.S.-Chinese relations and the current street unrest in many U.S. cities will have on the markets. They are also telling investors to consider the possibility of a second COVID-19 wave later this year.

European stocks were mixed Monday with major indexes in London and Paris up 1%, and Frankfurt down nearly 2%.

Asian markets were also higher Monday with major indexes in Hong Kong, Shanghai, Tokyo and Seoul all up.