U.S. stock futures slipped on Tuesday as investor skepticism about the sustainability of the recent tech rally weighed on Wall Street.

Japan’s key stock indexes soared to record highs on Friday, with the benchmark Nikkei index closing above the 52,000 mark for the first time, buoyed by strong gains in technology shares following robust earnings reports from major U.S. tech companies.

Japan’s key Nikkei stock index closed Wednesday at a record high above 51,000, led by strong technology shares after semiconductor sector heavyweight Advantest Corp. raised its earnings outlook.

Asian shares traded mixed on Friday following strong tech-driven gains on Wall Street, which pushed U.S. benchmarks to new record highs.