* Tesla drops after saying crashed car was on autopilot
* Humana up after report Walmart discussing tie-up, acquisition
* Amazon falls after Trump again targets the online giant
* Indexes down: Dow 0.19 pct, S&P 0.67 pct, Nasdaq 1.18 pct (Updates to open)
By Sruthi Shankar
April 2 (Reuters) - A dreadful week for technology stocks worsened on Monday as Amazon and Tesla shares fell further, setting a grim tone for markets already worried about China's decision to raise import tariffs on U.S. products.
Amazon dropped as much as 3 percent after President Donald Trump launched his latest attack over the pricing of the world's biggest online retailer's deliveries through the U.S. postal system and promised unspecified changes.
The stock was the biggest drag on the S&P 500 and the Nasdaq and weighed the most on the S&P consumer discretionary index, which fell 1.32 percent.
The Facebook data scandal, self-driving car crashes and Trump's intervention against Amazon pushed the S&P technology sector to post its worst monthly losses in nearly two years in March.
Facebook was down 1.7 percent on Monday, while the other FANG constituents like Netflix, Google-parent Alphabet were down between 2 percent and 3 percent.
Tesla shares shed more than 5 percent ahead of the electric car maker's announcement of quarterly production numbers for its crucial Model 3 sedan.
China, late on Sunday, said it would increase tariffs by up to 25 percent on 128 U.S. products, escalating a spat between the world's biggest economies. The move came in response to U.S. duties on imports of aluminum and steel.
"That's going to start stoking fears of trade wars and protectionism. The market doesn't really like that," said Andre Bakhos, managing director at New Vines Capital LLC in Bernardsville, New Jersey.
"And if it escalates, the questions could be on if China is going to buy our bonds. We have speculation out there, but it could be some profit taking and some risk-off mentality for the moment."
Trump is separately preparing to impose tariffs of more than $50 billion targeting "largely high-technology" Chinese products.
At 9:56 a.m. ET, the Dow Jones Industrial Average was down 46.7 points, or 0.19 percent, at 24,056.41.
The S&P 500 was down 17.81 points, or 0.67 percent, at 2,623.06 and the Nasdaq Composite was down 83.60 points, or 1.18 percent, at 6,979.84.
Ten of the 11 major S&P sectors were lower, with only utilities gaining.
Facebook was down as the data scandal last month continued to weigh. On Monday, brokerage Pivotal Research slashed its price target, citing a faster-than-expected deceleration in the social media company's revenue growth.
Humana jumped about 7 percent after a report that Walmart was in early-stage talks with the health insurer about developing closer ties, with acquisition discussed as one possibility. Walmart fell more than 2 percent.
Declining issues outnumbered advancers on the NYSE for a 1.78-to-1 ratio and for a 2.03-to-1 ratio on the Nasdaq. (Reporting by Sruthi Shankar in Bengaluru; Editing by Sriraj Kalluvila)