2. Emerging markets and developed economies
Table 1 compares the synchronicity of stock returns in some representative
stock markets during the first 26 weeks of 1995. Data from other periods in the
1990s display similar patterns. In emerging markets like China, Malaysia, and
Poland, over 80% of stocks often move in the same direction in a given week. In
Poland, 100% of traded stocks move in the same direction during four of the
twenty six weeks. In contrast, Denmark, Ireland, and the United States lack any instances of more than 57% of the stocks moving in the same direction during
any week, despite a rising market in the United States. Fig. 1 contrasts Chinese,
Malaysian and Polish stocks with U.S. stocks. For clarity, Fig. 1 omits the data
for Denmark and Ireland. As Table 1 shows, the stocks data for Denmark and
Ireland closely resemble the returns in the U.S. market.
We can easily reject the trivial explanation based on the Law of Large
Numbers that markets with many stocks should show less dispersion around the
mean. First, the stock markets of Denmark and Ireland resemble the U.S.
market, despite listing substantially fewer securities than China or Malaysia.
Below we shall show that stock price co-movement is negatively correlated with
per capita income, regardless of market or economy size. Second, the contrast
between the U.S. market and emerging markets is too stark to be based solely on
a statistical artifact. To test these differences, we calculate