 S&P 500 has climbed 17% this year, fueled by investor excitement over artificial intelligence that has sent shares of stocks like Nvidia and its fellow tech giants to dramatic heights. The growing size of the index heavyweights means a lot is riding on their ability to deliver profits and guidance in coming weeks that justify their sky-high valuations. Overall, companies in the S&P 500 are expected to report a fourth straight quarter of earnings growth, with net profits projected to have climbed 8.8% from last year's second quarter.