The ups and downs of share prices in markets around the world are often linked to each other.

At the beginning of this year, the confrontation between Iran and the United States pushed down the stock markets in many countries. The signing of the first phase of a U.S.-China trade agreement led to the rise in share prices in a number of markets. Share prices in markets across the globe will likely go up or down in union in response to such news.

However, long-term trends in share prices differ much from country to country. Share prices in countries like China — whose economy as a whole continues to grow rapidly — aside, big differences are observed in stock market movements among advanced industrialized nations, where the rates of economic growth differ little from each other. During the five years to the end of 2019, the Euro Stoxx index in Europe rose 19 percent, the Nikkei average on the Tokyo Stock Exchange increased 35 percent and the Dow Jones Industrial Average on the New York market surged 60 percent. Economists have given various theories as to why the U.S. is experiencing a particularly rapid climb in stock prices.