** "Magnificent Seven" group of megacap stocks down in premarket trading as worries mount that sweeping U.S. tariffs would hurt global economy
** Tesla TSLA.O leading losses with a 4.5% decline, while Nvidia NVDA.O down 3.5%; Meta Platforms META.O and Amazon.com AMZN.O down ~2% each
** Apple AAPL.O, Microsoft MSFT.O and Alphabet GOOGL.O dip 0.7%-1.4%
** Stocks across the world fell sharply on Monday after U.S. President Donald Trump said on Sunday that reciprocal tariffs he is set to announce this week will include all nations
** S&P 500 .SPX index is down 5.1% YTD, through last close