A Bank of America Corp. strategist who correctly predicted this year’s rebound in the widely-followed 60/40 portfolio strategy has warned that the trade could now be set for a sharp reversal.

The strategy that involves placing 60% of a portfolio in stocks and 40% in bonds had its best month in November since a rally that followed the break up of the Soviet Union more than 30 years ago, according to BofA. An analysis of historical data conducted by the strategist Michael Hartnett and his team shows that typically “pullbacks follow monster months.”

Stocks and bonds rallied in tandem last month — with the S&P 500 and 10-year Treasuries returning a combined 12% — as traders grew more confident that the Federal Reserve has finished raising interest rates. US stocks and bonds have only posted combined monthly returns of 12% or more 10 times over the past 40 years, according to data compiled by Bloomberg.

A Bloomberg benchmark that measures cross-asset market performance in the US shows a typical 60/40 portfolio gained about 14% this year after its worst year since the global financial crisis. Hartnett forecast at the end of last year that the strategy would recover in 2023.

This article was provided by Bloomberg News.