U.S. stock futures higher after strong earnings reports

(Reuters) - U.S. stock index futures were higher on Friday after three straight days of losses as Amazon, Visa and Starbucks beat expectations.

* Amazon.com shares jumped 18.3 percent to $570.56 in premarket trading, a day after the online retailer posted an unexpected quarterly profit.

* Dow component Visa was up 4.7 percent at $75.15 after the credit and debit card company's results handsomely beat expectations.

* Starbucks rose 4.3 percent to $59 after the world's biggest coffee chain reported a higher quarterly profit.

* U.S. stocks ended lower on Thursday, with the blue-chip Dow Jones industrial average slipping back into the red for the year, after disappointing corporate results and forecasts added to concerns about the U.S. profit outlook.

* Second-quarter S&P 500 earnings have been mixed, with 75 percent of companies so far beating analysts' profit expectations but just 52 percent surpassing revenue expectations, according to Thomson Reuters data.

* Adding to the concerns regarding lukewarm earnings, the S&P 500 is relatively expensive, trading at 16.9 times forward 12 months' earnings, above the 10-year median of 14.7 times, according to StarMine data.

* Investors will continue to focus on earnings report with nearly half of the S&P 500 companies having reported results.

* Biogen fell 5.7 percent to $363 after the biotechnology company's forecast came in below consensus.

* American Airlines rose 2.1 percent to $43.50 after the company's quarterly profit beat estimates.

* Data expected of Friday includes new single-family home sales for June, which is likely to remain steady at 0.546

million units. The data is expected at 10 a.m. ET (1400 GMT).

* Financial data firm Markit's preliminary Manufacturing Purchasing Managers' Index for July is expected to be unchanged at 53.6. The numbers are expected at 9:45 a.m. ET.

Futures snapshot at 7:16 a.m. ET:

* S&P 500 e-minis were up 3 points, or 0.14 percent, with 77,068 contracts traded.

* Nasdaq 100 e-minis were up 12 points, or 0.26 percent, on volume of 14,346 contracts.

* Dow e-minis <1YMc1> were up 19 points, or 0.11 percent, with 9,214 contracts changing hands.

(Editing by Don Sebastian)