Tweaking the way you invest in the S&P 500 may position your portfolio well for the next big market rotation.When investors talk about the market, they're usually talking about the S&P 500 (^GSPC +0.32%). Today, investing in the S&P 500 means having about 40% of your money in 10 stocks.In other words, stock investing has become incredibly concentrated. The artificial intelligence (AI) boom and the bull market in the "Magnificent Seven" stocks means that many investors are at risk of a deeper drawdown if the ...