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* Futures down: Dow 0.22%, S&P 0.27%, Nasdaq 0.54%
By Amy Caren Daniel
July 24 (Reuters) - U.S. stock index futures dropped on Wednesday, pressured by a fall in big tech companies after the announcement of a broad antitrust investigation by the U.S. Justice Department into the sector.
With second quarter earnings heating up, the day's centerpiece should be results for industrial bellwethers including Caterpillar and Boeing.
While the Justice Department did not identify specific companies, the terms of the review pointed to Alphabet Inc , Amazon.com Inc and Facebook Inc. The latter also reports later on Wednesday and is expected to be the subject of another regulatory fine this week.
Shares in the all three companies - among Wall Street's most highly valued by market cap - fell between 0.8% and 1.3%.
By 6:37 a.m. ET, initial futures prices were pointing to a roughly quarter point fall for the Dow Jones Industrial and S&P 500, while the tech-heavy Nasdaq was on course to open half a percent lower.
Shares in planemaker Boeing Co were down 0.6% as markets awaited a fuller update on the impact of the worldwide grounding of its lucrative 737 MAX passenger jets after two deadly crashes. The company has already said it would take a roughly $5 billion charge for the affair this quarter.
Heavy equipment marker Caterpillar was also set to report results before the bell.
The second quarter earnings season is off to a strong start, with nearly 80% of the 104 S&P 500 companies topping earnings expectations, and overall profits are expected to rise about 1%, according to Refinitiv, improving from a small decline estimated previously.
While investors in general had dialled down forecasts for this and next quarter, expectations that the Federal Reserve will cut interest rates at its policy-setting meeting next week have made traders more optimistic about the next year and more willing to buy stocks.
The S&P 500 and Nasdaq, having fallen back sharply in a sell-off in May, are back trading at or around record highs.
The global outlook is still shaky. Surveys earlier on Wednesday showed euro zone business growth was much weaker than expected in July, hurt by a deepening contraction in manufacturing, and suggested conditions would get worse next month.
The pick of the results from Tuesday's after-market results releases was Texas Instruments Inc, up 6.6% after the chipmaker said that a global slowdown in microchip demand would not be as long as feared.
At 6.37 a.m. ET Dow e-minis were down 59 points, or 0.22%. S&P 500 e-minis were down 8 points, or 0.27% and Nasdaq 100 e-minis were down 43.25 points, or 0.54%. (Reporting by Amy Caren Daniel in Bengaluru)