US STOCKS-Wall St lackluster as oil prices weigh on positive data
* July U.S. producer prices rise; industrial output up
* Energy stocks hit as US crude hits 6-1/2-year low
* King Digital, El Pollo Loco slump as results disappoint
* J.C. Penney, Nordstrom rise after strong results
* Indexes: Dow up 0.14 pct, S&P up 0.07 pct, Nasdaq down 0.18 pct (Updates to early afternoon)
By Tanya Agrawal
Aug 14 (Reuters) - The Dow and the S&P 500 eked out marginal gains in afternoon trading on Friday, and were set to post slight gains for the week, as the optimism from strong economic data was tempered by weak oil prices that weighed on energy stocks.
The Nasdaq fell, dragged down by biotech and chip stocks, and was poised to close lower for the week.
U.S. producer prices rose for a third straight month in July, suggesting the drag on inflation from weaker oil prices was easing, while industrial output advanced at its strongest pace in eight months in July. Continuación...