Tech-heavy stock markets are bracing for their heaviest weekly falls in seven months with investors uneasy about how far the rally in artificial intelligence stocks has run, while safer assets such as bonds and the yen went higher.S&P 500 futures and Nasdaq 100 futures were a touch firmer in the Asia morning, but overnight the Nasdaq dropped 1.9 per cent.For the week so far the world’s biggest tech index is down 2.8 per cent, which if sustained would mark its largest one-week drop since March and a jolt for ...