The U.S. job market notched its weakest monthly gain in more than five years, knocking down expectations for a Federal Reserve rate increase and stirring worries about the seven-year-old economic expansion.

Employers added 38,000 jobs in May, the weakest performance since September 2010, the Labor Department said Friday. The unemployment rate, obtained from a separate survey of households, fell to 4.7% from 5% in April largely due to a steep decline in labor-force participation.

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