U.S. stock index futures signaled shares would extend their sharp selloff on Wednesday, as they dropped after a report said tech major Apple had shelved its plan to increase production of its new iPhones on weak demand.

Shares of the world's most valuable public company fell 3.6% after Bloomberg reported that Apple had told suppliers to curtail efforts to increase assembly of its flagship iPhone 14 product family by as many as 6 million units in the second half of this year.

Other megacap growth names such as Amazon.com Inc, Microsoft Corp, Meta Platforms Inc and Tesla Inc fell between 0.8% and 1.2% in premarket trading with U.S. 10 year bond yields back at their highest since 2010.

Chipmakers Advanced Micro Devices, Qualcomm Inc Nvidia Corp and Micron Tech fell between 1.6% and 2.5%.

The report added to investor worries that include the U.S. Federal Reserve's aggressive monetary policy tightening as it seeks to tame stubbornly high inflation even at the risk of tipping the economy into a recession.

At 5:10 a.m. ET, Dow e-minis were down 232 points, or 0.79%, S&P 500 e-minis were down 35.5 points, or 0.97%, and Nasdaq 100 e-minis were down 151.25 points, or 1.33%.

Wall Street sank deeper into a bear market on Tuesday, with the S&P 500 recording its lowest close in almost two years.

Bucking the trend, Biogen surged 51% in ppremarket trade after its Alzheimer's drug, developed with Japanese partner Eisai's 4523.T>, succeeded in slowing cognitive decline.

Shares of Eli Lilly & Co, which is also developing an Alzheimer's drug, rose 7.8%. (Reporting by Susan Mathew in Bengaluru; Editing by Vinay Dwivedi)