President Trump’s promise to take tough action against China’s unfair economic practices was one of his most popular campaign ideas. But as the United States prepares stiff trade measures and China retaliates, stock markets have plummeted and some of America’s biggest companies are pushing back. Industry giants like General Electric and Goldman Sachs, as well as agricultural companies, have lodged objections with the White House, saying that tariffs on both sides of the Pacific and limitations on investments will cut off American companies from the world’s most lucrative and rapidly growing market.