Stocks plunged on Wednesday with the Dow Jones Industrial Average booking its worst single-day of trading for the year. Markets initially turned sharply lower after the U.S. bond market flashed its brightest warning signal yet presaging a potential recession.

Here were the main moves in the market, as of 4:00 p.m. ET:

• S&P 500 (^GSPC): -2.93%, or 85.72 points

• Dow (^DJI): -3.05%, or 800.49 points

• Nasdaq (^IXIC) : -3.02%, or 242.42 points

• 10-year Treasury yield (^TNX): -9.1 bps to 1.589%

• U.S. dollar to onshore Chinese yuan rate (CNY=X): -0.2429% to 7.0223

The yield on the 2-year U.S. Treasury note rose above that of the 10-year U.S. Treasury around 6 a.m. ET Wednesday, marking the first inversion of this closely watched portion of the yield curve in more than a decade.

Inversions of the yield curve – or when shorter-term yields rise above longer-term yields – are taken as bearish signals, since they indicate investors have less confidence in the short-term outlook and are instead bidding up Treasurys on the longer end of the curve. On Wednesday, the 30-year yield sank to as low as 2.025% during intraday trading, according to CBOE data, reaching the lowest level on record.

[Read more: Recession indicator flashes red for the first time since 2005]

An inversion between the 2-year and 10-year yields is especially widely viewed as a reliable recessionary harbinger. This particular occurrence follows an inversion of the 3-month and 5-year Treasury yields, which first inverted in December, as well as an ongoing inversion of the 3-month and 10-year Treasury yields.

Ahead of the Great Recession, the curve between the 2-year and 10-year yields first inverted in late 2005, before wavering in and out of an inversion for the next two years into the start of the recession, which officially began in December 2007.

Wednesday afternoon, President Donald Trump weighed in with a Twitter post, recapitulating his attack on the Federal Reserve and Fed Chair Jerome Powell and assailing the “crazy inverted yield curve.”

The yield curve for U.S. Treasurys has flattened recently as concerns over global growth and U.S.-China trade uncertainty weighed on investor sentiment. On Wednesday, signs of a slowdown abroad mounted further, with new data showing output in China’s key industrial sector fell to a more than 17-year low, amid an ongoing trade war with the U.S.