Just as a corporate balance sheet can provide insights into a company’s financial health, a “global balance sheet” (GBS), tallying the assets and liabilities of governments, corporations, households, and financial institutions, can do the same for the world economy. That logic drove the McKinsey Global Institute (MGI) to begin compiling, and regularly updating, a GBS covering 10 countries that together represent more than 60% of world GDP.

MGI’s first GBS, released in late 2021, showed that during the first 20 years of this century, global assets grew faster than output. In 2020, assets on the world...