The S&P 500 posted its best quarterly gains since 2013 last Friday. That came despite a quarter which saw further escalation in the U.S.-China trade war, with both countries slapping new tariffs on each other.
Washington has also threatened to impose additional duties on all Chinese imports going into the United States.
Trade jitters, coupled with a higher interest rate environment as the U.S. Federal Reserve raises rates, have rattled emerging markets in recent months. Turkey and Argentina were among the worst hit as they battled economic crises in their own countries.
Meanwhile, European markets continued to be rocked by political turmoil stemming from Italy.
Italy's government set a budget deficit target at 2.4 percent of gross domestic product over the course of 2019 to 2021. The previous administration had targeted a deficit of 0.8 percent of GDP in 2019 and a balanced budget in 2020.
Data released over the weekend also showed a slowdown in China's manufacturing sector in September, with both external and domestic demand weakening. The Caixin/Markit Manufacturing Purchasing Managers' Index — which focuses on small and medium-sized firms in China — fell to 50.0 in September from 50.6 in August. Economists polled by Reuters had expected a reading of 50.5 on average.
— Reuters contributed to this report.