David Koch, who built one of the nation's largest private businesses with his brother Charles and pumped money into conservative groups to help reshape American politics, has died.

Charles Koch confirmed the news in a statement on Friday that referenced David's long-running ailment.

Updated at 11:35 a.m. ET

Signaling the possibility of more interest-rate cuts, Federal Reserve Chairman Jerome Powell said the central bank will "act as appropriate" to sustain the economic expansion as the trade war with China takes a toll on global growth and the U.S. economy.

Wyoming, which is among the reddest of Republican states and a bastion of free enterprise, thinks it may have found a way to end crippling air ambulance bills that sometimes top $100,000 per flight.

The state's unexpected solution: Undercut the free market, by using Medicaid to treat air ambulances like a public utility.

Updated at 12:04 p.m. ET

President Trump promised to respond Friday after China said it will slap tariffs on $75 billion of autos and other U.S. goods. And he "ordered" U.S. companies to stop doing business with China.

U.S. stock markets fell sharply after Trump's tweets on China. The Dow Jones Industrial Average was down more than 400 points. Both the Dow and the S&P were down about 1.7% in late morning trading.

When childhood cancer is diagnosed early and treated effectively, the survival rate is impressive. In the United States, for example, the five-year survival rate for children with cancer is 80 percent.