The 60/40 portfolio is obsolete because bonds, laden with credit risk, no longer offer safety. A resilient modern portfolio requires a broader mix of uncorrelated assets: cash, gold, currencies, commodities like oil and food, and short-term government debt, while actively avoiding corporate credit.

The traditional 60/40 portfolio relied on a negative stock-bond correlation, which has now turned positive. As investors seek diversification, a decade-long structural shift towards a 60% stock, 20% bond, 20% commodity allocation could create a massive, sustained tailwind for energy and gold stocks.

Howard Marks offers a crucial corollary to Einstein's famous quote. For investors, the real insanity is failing to recognize a paradigm shift. Applying strategies that worked during 40 years of falling interest rates to the current, different environment is a recipe for failure. The context determines the outcome.

The entire modern financial system was built on the historically anomalous assumption of a negative correlation between stocks and bonds. The market is now reverting to its historical norm of positive correlation, invalidating traditional portfolio construction like 60/40.

Advisors who recommend fixed allocations like 60/40 without considering current expected returns and risk are committing a form of 'malpractice.' Investment decisions must be dynamic, as the relationship between risk and return is not constant over time.

The historical negative correlation between stocks and bonds, which underpins the 60/40 portfolio, breaks down when inflation rises above 2%. In this environment, they tend to move together, making bonds an ineffective diversifier and forcing investors to seek new solutions for equity risk.

The popular 60/40 stock-bond split traces its roots to the Wellington Fund during the 1929 crash. Its heavy bond allocation meant it was "crushed way less" than all-equity peers. Its fame grew not from high returns but from superior relative performance during a catastrophe.

The world's most common balanced portfolio doesn't have a rigorous academic origin. It evolved from the Wellington Fund, created by Walter Morgan in the late 1920s as a bond-heavy strategy to avoid the devastation of a major stock market crash.

For 40 years, falling rates pushed 'safe' bond funds into increasingly risky assets to chase yield. With rates now rising, these mis-categorized portfolios are the most vulnerable part of the financial system. A crisis in credit or sovereign debt is more probable than a stock-market-led crash.