July 28 (Reuters) - Nasdaq futures fell on Tuesday, mirroring a cautious mood across global markets toward AI chip stocks on concerns about hefty corporate spending and rising Chinese competition, ahead of earnings from some of the biggest companies on Wall Street.

Chip bellwethers such as Nvidia fell 1.1%, Micron slid 4.6% and Applied Materials lost 3.5% in premarket trading, while U.S.-listed shares of Taiwan's TSMC and Korea's SK Hynix fell 2.6% and 4%, respectively.

Global markets have become increasingly volatile this month as investors scrutinized the need for more corporate spending on AI infrastructure, such as semiconductors that underpinned strong gains in chip stocks in the previous quarter. 

Roundhill's Memory Exchange Traded Fund lost 6.6% on Tuesday and has been trading below its 50-day moving average for the past two weeks, reflecting a weak short-term momentum, while the Philadelphia SE Semiconductor Index has fallen over 20% from its all-time high hit in June. 

Signs that Wall Street's biggest companies such as Alphabet and Tesla are running out of cash to fund their ambitions have also made markets nervous, while China showcases cheaper AI models and deepens its presence in the competitive semiconductor industry.  

When AI hyperscalers Amazon.com, Meta, Apple and Microsoft report earnings later this week, investors will be keen to see if their investments, worth over several hundred billion dollars, are yielding returns. The reports are also expected to offer clues on the demand for chips and other AI infrastructure.     

Shares of the four U.S. companies were marginally higher in premarket trading on Tuesday.

At 04:27 a.m. ET, Dow E-minis were up 100 points, or 0.19%, and S&P 500 E-minis were down 6.5 points, or 0.09%. Nasdaq 100 E-minis were down 194.5 points, or 0.69%.

The Federal Reserve is also due to announce its interest rate verdict on Wednesday at the end of its two-day meeting. Traders only see a 37.4% likelihood for a rate hike this week, according to LSEG-compiled data, but are confident that borrowing costs could rise by at least 25 basis points by the end of the year.

   Offering both the Fed and investors some relief, oil prices fell 2.8% to a one-week low as a fragile ceasefire between the U.S. and Iran held up despite drone attack reports out of Saudi Arabia, Jordan and Iraq.

U.S. President Donald Trump said the United States was having "good talks" with Iran and there was a chance of a deal to end the conflict.

(Reporting by Johann M Cherian in Bengaluru; Editing by Shinjini Ganguli)