The ratio reveals distinct multi-decade cycles of regional equity leadership. The 1970s and early 1980s saw the ratio decline as commodity-driven economies and international markets outperformed the inflation-plagued US. The 1980s-1990s marked a powerful reversal as US stocks surged on the back of financial deregulation, technology innovation, and falling interest rates. The 2000s brought another rotation as emerging markets boomed and non-US stocks benefited from the commodities supercycle. The post-2008 period, however, has witnessed the most dramatic and sustained US outperformance in the entire dataset, driven by the dominance of FAANG stocks, exceptional US corporate earnings growth, and the dollar's strength. By the 2020s, US stocks represent over 60% of global market capitalization—an extreme concentration that rivals historical peaks—raising questions about mean reversion and whether international diversification will finally reward patient investors.

Major market events are clearly visible on this chart. During the COVID-19 crash in March 2020, both assets briefly showed negative YoY returns, but Bitcoin rebounded much more dramatically while the S&P 500 returned to modest positive territory. The 2022 bear market saw both assets decline in tandem, highlighting increased correlation during stress periods. Bitcoin's YoY performance has consistently shown much higher highs (during 2017 and 2021 bull runs) and lower lows (in bear markets) compared to the S&P 500's more modest fluctuations.