BMO Capital Markets forecasts the S&P 500 will reach 6,700, reflecting a gain of 13.2%. Chief investment strategist Brian Belski said he and his team "remain resolutely bullish," but expect "performance and fundamentals will more closely match the historical norms -- namely, in the high-single digit/low-double-digit percentage range in 2025."

A soft finish to 2024 still left stocks with a second straight stellar year. The S&P 500 logged a 23.3% gain, which follows a 24% rise in 2023. The combined gains of more than 53% was the largest two-year percentage jump for the index since year-end 1998,