Further weighing on U.S. stocks, oil prices slipped to a three-week low as increased Libyan production fueled concerns that the Organization of Petroleum Exporting Countries’ output cuts were being undermined by several countries excluded in the deal.

“With oil also down, the thoughts of an economic slowdown start to come up in people’s minds and has created a pause in the market euphoria,”  Andre Bakhos, managing director at Janlyn Capital, told Reuters.

Oil companies in the S&P 500 dipped 0.5% Wednesday while West Texas Intermediate crude oil futures decreased 2.6% to $48.4 per barrel and Brent crude was 3.0% lower to $50.3 per barrel.

Nevertheless, U.S. markets climbed in May on upbeat first-quarter corporate earnings and signs of a steadily improving global economy, despite falling commodity prices and rising political concerns.

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