When Apple cut its quarterly revenue forecast in January 2019, that announcement erased $74 billion from the company's value.
In the call with stock market analysts, Cook said that while Apple faced sales pressure in some emerging markets, he "would not put China in that category."
But then, in January, he admitted "in fact, most of our revenue shortfall to our guidance, and over 100% of our year-over-year worldwide revenue decline, occurred in Greater China across iPhone, Mac and iPad."
That lowered revenue forecast was Apple's first since the iPhone was launched in 2007.
In the lawsuit, the investors claim they lost billions because Mr Cook's statements on the November 1, 2018, earnings call were materially false and misleading.
Cases aren't just for iPhones
Judge Rogers rejected Apple's motion to dismiss the case, though she trimmed the lawsuit slightly by rejecting several of the shareholders' allegations. The dismissed claims concern sales of the iPhone XS and XS Max.
In her 23-page decision, she agreed it "strains credulity" that at the time of the earnings call, Cook would not have known about ongoing US-China trade tensions and their likely affect on Apple's sales.
It was only a few days after the earnings call that Apple told suppliers to curb production.
Apple has denied they defrauded or intended to defraud the company's investors.
However, the investors made a "cogent and compelling inference that Cook did not act innocently or with mere negligence" in his earnings call statements, said Judge Rogers.
He's arguing that Apple has fallen foul of the Securities Exchange Act of 1934, by misrepresenting the condition of its business in its largest growth market.
Disclosing false financial information violates the Act, and investors can also sue under the Act's Rule 10b-5 when companies have failed to communicate relevant information to them.
The Act was proposed by President Franklin D. Roosevelt's administration as a response to irresponsible financial practices preceding the 1929 US stock market crash.
It is now the basis for regulating the US financial markets and their participants.
This is not Apple's only recent trip to the US courts.
In March, it agreed a settlement of up to $500 million to end another class action lawsuit, also in the US district court for Northern California, claiming it intentionally slowed down certain iPhone models to encourage customers to upgrade.
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