S&P 500 Rally Stalls as Earnings Season Picks Up: Markets Wrap 7 minutes (Bloomberg) — Stocks struggled to gain traction as traders waded through a deluge of corporate results for clues on whether the market will be able to extend this year’s record-breaking advance. Following its biggest rally since early June, the S&P 500 fluctuated. United Parcel Service Inc. — an economic barometer — headed toward its largest plunge on record amid a profit miss. Tesla Inc. and Alphabet Inc. are due to kick off the “Magnificent Seven” earnings season after the close. Companies will have to impress as expectations…