Sell-side strategists, who have rushed to upgrade their stock targets ever since the market rebounded from its early-year slide, keep underestimating the rally’s strength. The record-setting advance has pushed the S&P 500 Index nearly 3% above the average year-end forecast among those tracked by Bloomberg, which currently stands at 6,486. Only in 2024 and 1999 have the calls lagged the market’s actual return so much around this time of the year.The gap underscores what a vexing spell it has been for Wall St ...