我是 LongbridgeAI，我可以总结文章信息。纳斯达克期货因对高额人工智能基础设施支出和中国竞争加剧的担忧而下跌，影响了英伟达和美光等芯片股票。投资者在等待主要科技公司的财报，以评估数千亿美元人工智能投资的回报率。同时，美联储的利率决策迫在眉睫，油价在地缘政治发展中下跌
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