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* Boeing falls after reporting $3 bln Q2 loss
* Caterpillar slips on lower quarterly earnings
* Texas Instruments hits record on upbeat results
* Big Tech faces broad Justice Dept antitrust probe
* Dow down 0.44%, S&P flat, Nasdaq up 0.13% (Changes comment, updates prices)
By Amy Caren Daniel
July 24 (Reuters) - U.S. indexes were off their session lows on Wednesday as a rally in semiconductor stocks on reassuring comments from Texas Instruments on global chip demand blunted the impact of weak earnings from bellwethers Boeing and Caterpillar.
Trade-sensitive Caterpillar Inc dropped 4.1% following disappointing earnings on weak sales in China, and higher production and restructuring costs.
Boeing Co slipped 2% after the world's largest planemaker posted its biggest loss in decades on the back of this year's grounding of its best-selling 737 MAX planes after two deadly crashes.
The bleak earnings dragged the blue-chip Dow index down more than 100 points, but the rise in chipmakers helped the S&P 500 and Nasdaq indexes to trade flat to slightly higher.
"Caterpillar's results are a reflection of the struggling manufacturing side and weak business spending," said Steve Chiavarone, a portfolio manager at Federated Investors in New York.
Texas Instruments Inc jumped 8.1% after the company hinted that a global slowdown in microchip demand would not be as long as feared, powering a 2.1% rise in the Philadelphia chip index to a record high.
"Texas Instruments greatly reflects the growing prospects of the industry at large," Chiavarone said.
The broader technology sector rose 0.16%, and provided the biggest support to markets.
Two weeks into the earnings season for which investors have dialed down expectations, about 77% of the 138 S&P 500 companies that have reported so far have topped earnings estimates, according to Refinitiv data.
Overall profits, however, are now expected to fall 0.1%, compared with prior estimate of a rise of about 1%.
At 10:58 a.m. ET, the Dow Jones Industrial Average was down 120.83 points, or 0.44%, at 27,228.36, the S&P 500 was up 1.08 points, or 0.04%, at 3,006.55. The Nasdaq Composite was up 10.49 points, or 0.13%, at 8,261.90.
United Parcel Service Inc climbed 8.8%, the biggest percentage gainer on the S&P 500 index, after the world's biggest package delivery company reported a better-than-expected quarterly profit.
Also weighing on sentiment was the U.S. Justice Department's announcement of a broad antitrust investigation into big tech companies.
The DoJ did not identify specific companies, but the terms of the review pointed to Alphabet Inc, Amazon.com Inc and Facebook Inc. Their shares fell between 0.3% and 0.6%.
Advancing issues outnumbered decliners by a 1.83-to-1 ratio on the NYSE and by a 1.39-to-1 ratio on the Nasdaq.
The S&P index recorded 28 new 52-week highs and no new low, while the Nasdaq recorded 51 new highs and 70 new lows. (Reporting by Amy Caren Daniel and Karina Dsouza in Bengaluru; editing by Patrick Graham, Saumyadeb Chakrabarty and Sriraj Kalluvila)