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* U.S.-China tariffs go into effect
* Trade-sensitive Boeing, Caterpillar drop premarket
* Facebook, Twitter drop on report of new U.S. draft order
* S&P sector reshuffle to debut, may boost volumes
* Futures down: Dow 0.13 pct, S&P 0.16 pct, Nasdaq 0.44 pct
By Shreyashi Sanyal
Sept 24 (Reuters) - U.S. stock index futures dropped on Monday as the latest round of Sino-U.S. tariffs kicked in, with neither showing signs of backing down from a protracted trade war.
The markets could be volatile and trading volumes higher as the S&P 500 sector shuffle takes effect, with the telecoms being folded into a new communications services index that will now include heavy-hitting technology stocks such as Facebook Inc , Twitter and Alphabet.
Shares of the three companies fell between 0.5 and 1 percent in premarket trading, also on renewed fears of higher regulation after a report that the White House has drafted a preliminary order to direct federal agencies to probe the business practices of social media and internet firms.
U.S. tariffs on some $200 billion worth of Chinese goods took effect on Monday, along with Beijing's retaliatory duties on $60 billion worth of U.S. products, which pressured trade-sensitive stocks.
Boeing, the biggest U.S. exporter to China, dropped 0.5 percent and Caterpillar 0.3 percent, leading the losers on the Dow Industrials before the bell.
The benchmark S&P 500 and the blue-chip Dow have fared better than the Nasdaq of late as the latest list of Chinese goods subject to tariffs include many technology products.
While the China market is closed for the Mid-Autumn Festival, U.S.-listed shares of Chinese firms fell. Alibaba was down 1.5 percent and Baidu 1.6 percent. JD.com, whose founder faces rape allegations, was last down 3.9 percent.
At 7:39 a.m. ET, Dow e-minis were down 35 points, or 0.13 percent. S&P 500 e-minis were down 4.75 points, or 0.16 percent and Nasdaq 100 e-minis were down 33 points, or 0.44 percent.
Shares of energy companies rose as oil prices jumped more than 2 percent to a four-year high after OPEC declined to announce an immediate increase in production despite calls by President Donald Trump to raise global supply.
Exxon Mobil gained 0.6 percent and Chevron 0.7 percent, making them the second- and the third-biggest gainers among Dow components. The biggest was Walt Disney's 1.1 percent gain.
Comcast fell 4.4 percent after it won an auction for Britain's Sky Plc, ending a battle with Twenty-First Century Fox and Disney. Fox rose 0.8 percent.
Pandora Media jumped 8.6 percent after satellite radio provider Sirius XM Holdings said it would buy the music streaming service in an all-stock deal valued at about $3.5 billion. Sirius fell 3.3 percent. (Reporting by Shreyashi Sanyal in Bengaluru; Editing by Anil D'Silva)