(Reuters) - U.S. stock index futures declined on Wednesday, with the tech-heavy Nasdaq leading losses after disappointing forecasts from Alphabet and AMD in a busy day for corporate earnings.

Google-parent Alphabet dropped 7.1% in premarket trading after posting downbeat cloud revenue growth and earmarking a higher-than-expected $75 billion for its AI buildout this year, fanning concerns about its hefty investments into the technology.

"While some investors may have hoped that Silicon Valley would exercise caution in the wake of China's AI innovations, the opposite is occurring," Jochen Stanzl, chief market analyst at CMC Markets, said in a mailed statement.

Advanced Micro Devices lost 9.1% after CEO Lisa Su said the company's current-quarter data center sales - a proxy for its AI revenue - would fall about 7% from the previous quarter.

Meanwhile, Apple shed 2.6% after Bloomberg News reported that China's antitrust regulator was preparing for a possible investigation of the iPhone maker.

At 07:08 a.m. ET, Dow E-minis were down 20 points, or 0.04%, S&P 500 E-minis were down 27.25 points, or 0.45%, and Nasdaq 100 E-minis were down 181.25 points, or 0.84%.

All three major Wall Street indexes closed higher on Tuesday, with energy shares outperforming, while an earnings-driven jump in Palantir boosted technology shares.

A January private payrolls reading is due at 8:15 a.m. ET on Wednesday, while a survey on U.S. services activity for the month is due shortly after markets open.

The all-important January nonfarm payrolls report is expected to be released on Friday.

Markets also looked for developments on the tariffs front.

U.S. President Donald Trump said on Tuesday he was in no hurry to speak to Chinese President Xi Jinping to try to defuse a new trade war between the countries, sparked by sweeping 10% U.S. tariffs on all Chinese imports.

Morgan Stanley joined Barclays and Macquarie in forecasting a single 25-basis-point interest rate cut by the U.S. Federal Reserve this year, citing uncertainty from Trump's tariff policy.

Fed Vice Chair Philip Jefferson as well as San Francisco Fed President Mary Daly on Tuesday reiterated the central bank's message that policymakers need not rush into easing rates further.

Comments from four Fed heads including Richmond Fed President Thomas Barkin will be on the radar through the day.

In other moves, FMC Corp plunged 21.3% after the agrichemicals producer forecast first-quarter revenue below estimates.

Chipotle Mexican Grill slid 5.6% after the burrito maker forecast tepid annual comparable sales growth and said if Trump's proposed tariffs against Mexico went into full effect, the company would take a roughly 60-basis-point impact on its raw material costs this year.

U.S.-listed shares of Chinese e-commerce firm PDD Holdings dropped 6.6% after a report that the U.S. was considering whether to add PDD's Temu to Homeland Security's "forced labor" list.

Walt Disney gained 1.4% after sharply outperforming quarterly earnings estimates.

(Reporting by Shashwat Chauhan and Sukriti Gupta in Bengaluru; Editing by Pooja Desai and Devika Syamnath)