Stocks declined and Treasuries outperformed in the following one-to-three months each time that happened, strategist Michael Hartnett wrote in a note. Stock markets are already showing signs of strain following a rally in the MSCI All-Country World Index this year, as investors worry about a potential bubble in artificial intelligence stocks. With investor exposure to stocks still the highest since February in the BofA survey, Hartnett said the market would “correct further” without an interest rate reduction next month.