This article appears as part of Casey Weade's Weekend Reading for Retirees series. Every Friday, Casey highlights four hand-picked articles on trending retirement topics and delivers them straight to your email inbox. Get on the list here.

Take real estate, for instance. It's often seen as a counterbalance to stocks, but recent data shows a growing correlation between the two. This means real estate might not be the reliable buffer you expect in a market downturn.

High-yield bonds are another commonly recommended diversifier. While less sensitive to interest rate swings than traditional bonds, their close ties to the stock market limit their protective power. Even cryptocurrencies, with their reputation for being uncorrelated, are extremely volatile and can experience significant losses.