Stocks have impressed once again in 2024, and Oppenheimer remains bullish.Javier GhersiUS stocks are set for another double-digit return in 2024 and can rally again next year.This year's gains have been broad-based, as large caps and mid caps are both thriving.Here are 12 smaller stocks to buy with up to 94% upside, according to Oppenheimer.Investors have been spoiled by US stocks' outstanding returns in recent years, and one firm says they should expect more of the same in 2025.The S&P 500 is less than two months away from clinching a double-digit return for the fifth time in six years.