Stock market heading for its worst week since June

Stock indexes are turning lower on Wall Street, putting the market on track for its worst week since early June.

Bank and energy stocks led the way lower. The Dow Jones industrial average was off 14 points at 13,311 shortly before midday Friday, giving up an earlier gain of 75.

The Standard & Poor's 500 index was off six points at 1,427 and the Nasdaq composite also lost six points to 3,043.

All three indexes are heading for their worst week since June following a mixed start to the corporate earnings season.

Wells Fargo fell $1.22 to $33.96, leading other bank stocks lower, after its revenue came in lower than analysts were expecting.

Semiconductor maker AMD plunged 30 cents to $2.90 after saying its third-quarter revenue would drop 10 percent.