Chinese tariff retaliation, presidential tweets and market unease sends exchanges plummeting

After a week of modest gains, major stock indexes plummeted on Friday as China retaliated against U.S. tariffs by imposing $75 billion worth of tariffs on U.S. goods coming into the country. China's foreign ministry said that it would resume tariffs on U.S. imports of automobiles and auto parts and place an additional 5% or 10% tariff on agricultural and food products like soybeans, coffee, whiskey and seafood.