(For a Reuters live blog on U.S., UK and European stock markets, click LIVE/ or type LIVE/ in a news window.) * Social media stocks rally after strong results * AmEx eyes record open on blowout Q2 profit * Futures up: Dow 0.52%, S&P 0.46%, Nasdaq 0.37% (Adds comments, details; updates prices) July 23 (Reuters) - Wall Street’s main indexes were set to open higher on Friday, helped by megacap technology stocks and strong earnings from social media companies Twitter and Snap, with investors eyeing business activity data later in the day. Twitter Inc gained 4.9% in premarket trading after it reported upbeat revenue growth, as the social media platform rolled out ad-targeting improvements to help brands reach potential customers. Snapchat-owner Snap Inc jumped 17.2% after it beat Wall Street estimates for users and revenue in the second quarter, notching the highest growth rates since late-2017. Strong results from the social media firms set a positive precedent for Facebook Inc, which rose 2.9% ahead of its second-quarter results next week. Other major tech names, including Amazon.com, Apple Inc, Microsoft Corp and Google-owner Alphabet Inc, were up between 0.3% and 1.7%. American Express Co gained 3.6% and was set to open at a record high as the credit card issuer beat estimates for second-quarter profit. “Earnings are expected to be much better for the value side than for growth, but with interest rates being as low as they are, investors will be sticking to growth because that way the near-term momentum is on their side,” said Sam Stovall, chief investment strategist at CFRA Research in New York. The second-quarter reporting season barreled ahead, with 104 companies in the S&P 500 having reported so far. Of those, 88.5% have beaten consensus estimates, the highest since 1994, according to Refinitiv data. Wall Street investors have shifted between growth stocks and economically sensitive value names this week, after concerns about the spread of the Delta coronavirus variant roiled markets and sparked a flight to the perceived safety of bond markets on Monday. The S&P 500 consumer discretionary and technology sectors were top gainers this week. The major indexes were set for their fourth weekly gain in five weeks on boost from a batch of strong earnings reports, while the blue-chip Dow Jones Industrial Average and the benchmark S&P 500 index inched closer to their record highs hit last week. Focus will also be on IHS Markit’s flash reading on manufacturing and services sectors for July, due at 09:45 a.m. ET. The Federal Reserve’s policy meeting next week will be closely watched for further hints about tapering amid a spike in COVI-19 cases, though Chair Jerome Powell has repeatedly said the labor market remains well short of its target. At 8:34 a.m. ET, Dow e-minis were up 181 points, or 0.52% and S&P 500 e-minis were up 20.25 points, or 0.46%. Nasdaq 100 e-minis were up 55.25 points, or 0.37%, hitting a record high and breaching 15,000 points for the first time. Intel Corp fell 2.5% after the chipmaker said it still faces supply chain constraints and gave an annual sales forecast that implied a weak end to the year. Schlumberger NV added 2% after it reported a rise in its second-quarter profit as oilfield activity rebounded. (Reporting by Devik Jain and Shreyashi Sanyal in Bengaluru; editing by Uttaresh.V and Maju Samuel) Our Standards: The Thomson Reuters Trust Principles.