Futures turn higher, but Fed jitters weigh; JCP gains

U.S. stock index futures edged higher Tuesday, after the Dow and S&P 500 logged their first four-day losing streaks this year, but ongoing anxiety about a possible imminent scaling back of the Federal Reserve's massive stimulus program roiled markets worldwide.

As global markets took their cue from Wall Street's losing streak, which extended into a fourth straight session on Monday -- its longest downward trend so far this year -- stock futures pointed higher as surging Treasury yields appeared to stabilize in early dealings.

European mining stocks took a hit on Tuesday after disappointing earnings from BHP Billiton and Glencore Xstrata. The European basic resources sector fell by over 2 percent after BHP Billiton reported a 15 percent drop in profits and Glencore Xstrata wrote down the value of assets inherited from Xstrata by $7.7 billion.

(Read more: Glencore takes $7.7 billion hit on Xstrata assets)

Meanwhile, emerging market stocks extended sharp losses in Asia. Indonesia's Jakarta Composite fell 4.5 percent, placing it in bear market territory, having lost 22 percent from May's all-time record high. Plus, Thailand's benchmark SET Index lost nearly 3 percent. Japan's Nikkei closed at a near two-month low and China's Shanghai Composite fell 0.6 percent.

(Read more: First India, then Indonesia... who is next?)

Among earnings, Home Depot posted second quarter earnings that topped expectations and raise its full-year guidance, citing the rebounding housing market.

JCPenney posted sales that continued to fall sharply last quarter, but the troubled retailer said the back-to-school season has so far been "encouraging." The company also said sales trend had improved every month in the quarter. Shares traded higher.

Best Buy surged after the consumer electronics retailer easily topped Wall Street expectations.

In other stocks news, Barclays declined after a U.S. appeals court said investors may revive a lawsuit that alleges the bank misled them about its subprime mortgage exposure.

Apple edged higher even after S&P Capital IQ downgraded the iPhone maker to "buy" from "strong buy." S&P Capital IQ equity analyst Scott Kessler said the stock was nearing his target price of $550, and noted that it had already risen 30 percent off a low set on June 27.