Stocks plunged Wednesday in the Dow Jones Industrial Average's worst performance of 2019 after the bond market flashed a troubling signal about the U.S. economy.

The Dow dropped 800.49 points or 3.05% to 2,5479.42, its worst percentage drop of the year and fourth-largest point drop of all time. The S&P 500 fell 85.72 points or 2.93% to 2,840.6, while Nasdaq Composite declined 3.02% to 7,773.94. The Dow gave up the entire rebound from a sell-off earlier in August and fell to a two-month low.

The yield on the benchmark 10-year Treasury note on Wednesday briefly broke below the 2-year rate, an odd bond market phenomenon that has been a reliable indicator of economic recessions. Investors, worried about the state of the economy, rushed to long-term safe haven assets, pushing the yield on the benchmark 30-year Treasury bond to a new record low on Wednesday.

Bank stocks led the declines as it gets tougher for the group to make a profit lending money in such an environment. Bank of America and Citigroup fell 4.6% and 5.3% respectively, while J.P. Morgan dropped 4.2%. The financials sector dipped into correction territory, down more than 10% from a recent high.

"The U.S. equity market is on borrowed time after the yield curve inverts," said Bank of America technical strategist Stephen Suttmeier, in a note.

There have been five inversions of the 2-year and 10-year yields since 1978 and all were precursors to a recession, but there is a significant lag, according to data from Credit Suisse. A recession occurred, on average, 22 months after the inversion, Credit Suisse shows. And the S&P 500 actually enjoyed average returns of 15% 18 months after an inversion before it eventually turns.