For decades, seasonal trends have favored the fourth quarter, thanks in large part to a boost around the holidays at the end of the year. Michael M. Santiago / Getty Images Close Key Takeaways It's been a good year for U.S. stocks so far. Some experts are calling for an even stronger finish. An uncharacteristically strong September—the month with a reputation as the worst for stocks—saw the S&P 500 add 3.5% after logging a series of fresh highs, bringing the benchmark index up close to 14% year-to-date. Tha ...