A historic global trade war, a proposed $1.2 trillion European fiscal bazooka and the emergence of China as tech race leader are upending global flows of money, marking a potential turning point for investor capital away from the United States. China unlocked more stimulus on Wednesday and promised greater efforts to cushion the impact of an escalating U.S. trade war. Hours earlier, Germany’s likely next government agreed on the biggest overhaul to fiscal policy since the country’s reunification. Meanwhile, U.S. economic data points to a weakening, and the trade war unleashed by U.S. tariffs that kicked in this week is...