New York (CNN Business) — Fear of an economic slowdown is rocking Wall Street and the oil markets.

The Dow briefly plunged below 23,000 on Thursday and the Nasdaq is flirting with a bear market. US oil prices plummeted more than 4% to the lowest level since August 2017.

The latest wave of selling shows how worried investors have become about the economy. Those jitters have been exacerbated by concern that the Federal Reserve is making a mistake by continuing to raise interest rates.

At Thursday’s lows, the Nasdaq was briefly on track to close 20% below the closing high set on August 29. The Dow also broke below the 23,000 level for the first time since October 2017.

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