You cannot understand the vulnerable state of the U.S. and global economies — and nervous stock markets — without coming to grips with the crash of “emerging-market” countries. Led by China, these are middle-income countries that, along with the poorest countries, account for 85 percent of the world’s population and 60 percent of the global economy, according to Christine Lagarde , head of the International Monetary Fund. In many ways, their voyage into the global marketplace is a triumph. Rapid economic growth, driven in part by trade and international investment, has catapulted hundreds of millions of people out of deep poverty. By World Bank estimates, about 13 percent of the world’s population lives on incomes of $1.90 a day or less , but that’s down from 37 percent in 1990 and 44 percent in 1981. Unfortunately, emerging-market countries are now disappointing in ways that damage the world economy. After […]