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* Pinterest plummets as 2019 forecast disappoints
* U.S. agrees to lift metal tariffs on Canada, Mexico
* Consumer sentiment hits highest in 15 years - UMich
* Luckin Coffee surges in market debut
* Dow up 0.9%, S&P off 0.9%, Nasdaq down 0.37% (Updates to late afternoon, changes dateline, byline)
By Stephen Culp
NEW YORK, May 17 (Reuters) - Wall Street struggled for gains in an up-and-down session on Friday as mixed headlines on trade dampened positive consumer sentiment data, sending investors into the weekend with little enthusiasm.
The Dow inched up, while the Nasdaq lost ground and the bellwether S&P 500 was nominally lower, hovering more than 2% below its record high reached on April 30. All three were on course for their second successive weekly declines after failing to fully recover from Monday's steep sell-off.
China added fuel to the fire of the increasingly rancorous trade war with the United States with a defiant front-page commentary on the Communist Party's People's Daily, ratcheting up tensions the day after U.S. President Donald Trump officially blacklisted Chinese telecom Huawei Technologies Co Ltd from doing business with U.S. companies.
Elsewhere in the multi-front U.S. tariff war, Trump confirmed he would delay imposing imported auto tariffs by as much as six months, and agreed to lift metal tariffs on Canada and Mexico.
Consumer sentiment jumped 5.3% in May to its highest reading in 15 years, according to the University of Michigan's consumer sentiment index. However, "the gains were recorded mostly before the trade negotiations with China collapsed and China responded with their own tariff," the university said.
"While the headlines are about trade the movement is more about global growth than those headlines," said Oliver Pursche, vice chairman and chief market strategist at Bruderman Asset Management in New York.
Tariff jitters dragged on key industrial shares.
Farm equipment maker Deere & Co was the biggest percentage loser on the S&P 500, dipping 6.4% after cutting its full-year forecast.
Caterpillar Inc, 3M Co, Textron, General Dynamics and Fedex Corp all helped pull the industrial sector 0.5% lower.
The Dow Jones Industrial Average rose 23.01 points, or 0.09%, to 25,885.69, the S&P 500 lost 2.54 points, or 0.09%, to 2,873.78 and the Nasdaq Composite dropped 28.94 points, or 0.37%, to 7,869.11.
Of the 11 major sectors in the S&P 500, eight were trading in the red, with energy and industrials seeing the largest percentage losses.
With 460 of S&P 500 companies having posted first-quarter results, 75.2% of which beat analyst expectations, the mostly upbeat first-quarter earnings season is nearly complete.
Analysts now expect first-quarter earnings growth of 1.4%, a significant turnaround from the 2% loss expected on April 1.
Applied Materials Inc advanced 4.1% after the company's better-than-expected quarterly profit eased concerns about waning chip demand.
Active wear company Under Armour Inc gained 7.3% following JP Morgan's upgrade of the stock to "overweight."
Pinterest Inc slumped 11.5% after its first quarterly earnings report as a publicly-traded company.
Shares of Luckin Coffee Inc jumped 24.6% as the Chinese challenger to Starbucks Corp made its debut.
Declining issues outnumbered advancing ones on the NYSE by a 1.91-to-1 ratio; on Nasdaq, a 1.76-to-1 ratio favored decliners.
The S&P 500 posted 29 new 52-week highs and 5 new lows; the Nasdaq Composite recorded 53 new highs and 87 new lows. (Reporting by Stephen Culp Editing by Bill Berkrot)