Price of crude oil drops on Thursday

The price of oil tumbled more than $4 a barrel, or 7%, on Thursday, marking its worst day in four years.

The broader market also dropped sharply Thursday and bond prices spiked after President Donald Trump announced the U.S. will slap a new 10% tariff on some $300 billion worth of goods from China beginning next month.

The news erased a broad rally on Wall Street, sending the Dow Jones Industrial Average from a gain of more than 250 points to close down 180.85 points, or just more than 1%. The S&P 500 had been on pace for its best day in nearly two months, but finished down 26.82 points, or 0.9%

The escalation in the long-running and costly trade dispute comes only a couple of days after both sides resumed negotiations. In a series of tweets, Trump noted that while the slow-moving trade talks have been "constructive," China has not followed through on some prior agreements, including the purchase of large quantities of U.S. agricultural products.

The new tariff would take effect Sept. 1. The U.S. has already applied tariffs of 25% on $ 250 billion worth of goods from China. Beijing has retaliated with tariffs on $110 billion in American goods, including agricultural products, in a direct shot at Trump supporters in the U.S. farm belt.

The large oil price drop dragged down most energy stocks, including many in Oklahoma.

Chaparral Energy Corp. shed 43 cents, or 12%, to $3.12, while WPX Energy Inc. closed down $1.08, or 10%, to $9.36. Chesapeake Energy Corp. shares were down 16 cents, or 8.8%, to $1.65, while Continental Resources Inc. dropped $2.90, or 7.8%, to $34.27.