How worried should retirees be that the Chinese stock market is now in a bear market—having dropped by more than 20%?
It’s an important question because it seems like few others are even paying attention. Wall Street appears to be comforted by the S&P 500 SPX, +0.10% being up for the year, if modestly. But that’s little solace for retirees whose portfolios are often significantly diversified into non-U.S. stocks.
How unusual is it for a leading foreign stock market to diverge so significantly from the U.S. market? When such divergences do occur, do they mean that the U.S. market is likely to soon catch up to the rest of the world, or vice versa?
It’s a cliché these days to say this, but the core insight that allows us to understand these and related phenomena is that the world’s financial markets have become increasingly interconnected—dramatically so, in fact. This means that, while the divergence we’re currently seeing between U.S. and Chinese stocks would not have been all that unusual many years ago, it has become increasingly rare in recent decades.
It’s easy to quantify the degree to which the markets have become interconnected. Take a look at the accompanying chart, which plots the correlation over the trailing five years between U.S. and foreign equities. A high coefficient (approaching +1) means that the two have more or less moved up and down in lockstep, while a low reading (closer to 0) means that the two march to the beats of separate drummers. (I constructed the chart by focusing on MSCI’s EAFE index, since for most of the last 50 years the Chinese economy and stock market were tiny compared with those of the U.S.)