Former President George W. Bush arrives for a funeral service for former President George H.W. Bush at St. Martin's Episcopal Church Thursday, Dec. 6, 2018, in Houston. (AP Photo/David J. Phillip, Pool)

Moroccan Foreign Minister Nasser Bourita, speaks during a press briefing about the final communique of the initial Roundtable on Western Sahara at the European headquarters of the United Nations in Geneva, Switzerland, Thursday, Dec. 06, 2018. (Martial Trezzini/Keystone via AP)

Specialist Peter Mazza, left, and trader John Panin work on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Tommy Kalikas works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Gregory Rowe works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Patrick Casey works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Specialist Philip Finale works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Specialist Anthony Rinaldi works at his post on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Robert Oswald works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Fred DeMarco works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Robert Charmak works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Thomas McCauley works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Trader Dudley Devine works on the floor of the New York Stock Exchange, Thursday, Dec. 6, 2018. U.S. stocks tumbled in early trading Thursday following a sell-off in overseas markets. (AP Photo/Richard Drew)

Traders work on the floor at the opening bell of the Dow Industrial Average at the New York Stock Exchange on December 6, 2018 in New York. - Wall Street opened sharply lower Thursday, joining a global stocks sell-off after the arrest of a key Chinese executive at Washington's request revived worries over trade tensions. About three minutes into trading, the Dow Jones Industrial Average had fallen 2.0 percent, nearly 500 points, to 24,532.25. The broad-based S&P 500 sank 1.9 percent to 2,648.04, while the tech-rich Nasdaq Composite Index shed 2.2 percent to 7,002.02. (Photo by Bryan R. Smith / AFP)

Traders work on the floor at the opening bell of the Dow Industrial Average at the New York Stock Exchange on December 6, 2018 in New York. - Wall Street opened sharply lower Thursday, joining a global stocks sell-off after the arrest of a key Chinese executive at Washington's request revived worries over trade tensions. About three minutes into trading, the Dow Jones Industrial Average had fallen 2.0 percent, nearly 500 points, to 24,532.25. The broad-based S&P 500 sank 1.9 percent to 2,648.04, while the tech-rich Nasdaq Composite Index shed 2.2 percent to 7,002.02. (Photo by Bryan R. Smith / AFP)

Traders work on the floor at the opening bell of the Dow Industrial Average at the New York Stock Exchange on December 6, 2018 in New York. - Wall Street opened sharply lower Thursday, joining a global stocks sell-off after the arrest of a key Chinese executive at Washington's request revived worries over trade tensions. About three minutes into trading, the Dow Jones Industrial Average had fallen 2.0 percent, nearly 500 points, to 24,532.25. The broad-based S&P 500 sank 1.9 percent to 2,648.04, while the tech-rich Nasdaq Composite Index shed 2.2 percent to 7,002.02. (Photo by Bryan R. Smith / AFP)