RBC Capital Markets strategists led by Lori Calvasina warn that the risk of a US stock pullback of up to 10% is increasing as midterm elections approach and markets enter a historically weak seasonal period. The team noted the S&P 500 has declined in September in five of the past 10 years. The midterm election cycle could inject volatility into the artificial-intelligence trade as AI becomes a campaign issue, while the ongoing Iran war remains an additional headwind for markets.