US stocks slip in midday trading and are heading for their biggest weekly loss since April

U.S. stocks are moving mostly lower in midday trading as investors assess corporate earnings.

The Dow Jones industrial average fell 28 points, or 0.2 percent, to 16,886 as of midday Eastern time Friday.

The Standard & Poor's 500 index lost two points, or 0.1 percent, to 1,962. The Nasdaq composite rose four points, or 0.1 percent, to 4,400.

Fastenal, which makes industrial fasteners, fell 5 percent after reporting revenue that fell short of analysts' estimates.

The S&P 500 index is poised for its biggest weekly loss since April after closing out the previous week at a record high. It's down 1.2 percent so far this week.

Bond prices rose. The yield on the 10-year Treasury note fell to 2.51 percent.