So, just how big are the Magnificent Seven tech companies?At $12.5 trillion — and likely a whole lot more after Friday — the combined market cap of Microsoft MSFT, +1.56%, Apple AAPL, +1.33%, Alphabet GOOGL, +0.76%, Amazon.com AMZN, +2.63%, Nvidia NVDA, +2.44% and Tesla TSLA, +0.84% is equal to the combined GDP of New, York, Tokyo, London, Los Angeles, Paris, Seoul, Chicago, San Francisco, Osaka, Dallas and Shanghai, according to Bank of America calculations.Related: Meta just joined Nvidia and Microsoft in ...