Foreign stocks are soaring and Americans are pouring money into them. But although overseas equities have captured investors’ fancy before, there’s a twist this time: More investors are embracing passive, index-style investing, ignoring the long-held belief that active managers can beat indexers by uncovering bargains in inefficient foreign markets. Have conditions really changed enough to make indexing pay off as well in foreign markets as it has in the U.S.? It may be too soon to know for sure. But international equity markets and American investor behavior are clearly evolving. “Whatever the argument was in the past for active versus passive, it’s different today,” says Richard J. Herring , professor of finance and international banking at Wharton. “It’s different today because the indices [that guide indexed investments] are better constructed.” Experts note that foreign stock index funds have begun to beat many actively managed competitors in recent years.…