U.S. stocks dipped in a broad sell-off on Monday as rising geopolitical tensions spooked investors away from equities and the extended U.S.-China trade war stoked fears of impending global recession.

All three major U.S. stock indexes started the week in the red, with few earnings reports and no economic data to soothe market jitters over protests in Hong Kong, the rejection of Argentine President Mauricio Macri's economic agenda in primary elections, and a tariff dispute that has beleaguered markets for months.

"It's the end of summer so a lot of market players aren't on the job," said Bucky Hellwig, senior vice president at BB&T Wealth Management in Birmingham, Alabama. "It happens seemingly every August where we have events that move the market out of proportion to the events."