RT Journal Article SR Electronic T1 Decoupling JF The Journal of Portfolio Management FD Institutional Investor Journals SP 59 OP 66 DO 10.3905/jpm.2002.319843 VO 28 IS 3 A1 Les Gulko YR 2002 UL https://pm-research.com/content/28/3/59.abstract AB The returns of U.S. stocks and Treasury bonds are usually positively correlated, or coupled. As the stock market plunges, Treasury bonds tend to rally, and the daily returns become negatively correlated, or decoupled. In this article, the author examines the decoupling that accompanies stock market crashes. He begins by presenting empirical evidence of the stock–bond decoupling and next examines some implications. The main practical implication is that U.S. Treasury bonds offer effective diversification during financial crises, at the time it is needed most. The main theoretical implication is that normal probability distributions (both conditional and unconditional) generally misspecify the joint returns of U.S. stocks and Treasury bonds.