For decades, the 60/40 stock-bond portfolio has been a popular strategy for diversification. Contrary to what we thought, stock and bond returns have not always had negative correlation; in fact, there was positive correlation throughout much of the late 1900s. In recent years, the stock-bond correlation has again become positive and is rising with inflation outside of central bank's target ranges. This means investors may be underestimating portfolio risk due to changing correlations between stocks and bonds and that more cautious investors may need to adjust their holdings accordingly. It is essential to reevaluate our strategies to match today's market dynamics in order to achieve true diversification.