The Dow Jones Industrial Average tumbled by more than 500 points on Monday as the equity benchmarks in the U.S. The Dow DJIA, -0.24% finished off 508 points, or 2.1%, at 23,592, marking its lowest since March 23, 2018, the S&P 500 index SPX, -0.16% declined by 2.1% at 2,545, finishing at its lowest level since Oct. 9, 2017, while the Nasdaq Composite Index COMP, -0.15% ended 157 points, or 2.3%, lower at 6,754, putting in its lowest finish since November of 2017, according to Dow Jones Market Data. The declines come fresh off an ugly Friday session that saw the Dow enter correction territory, widely defined as a drop of at least 10% from a recent peak. Meanwhile, the 10-year Treasury note TMUBMUSD10Y, 0.665% was yielding 2.86%, pulling back from its Friday values, indicating buying in government bonds and a so-called risk-off mode in the market with investors fleeing to the perceived risk government bonds. Bond prices rise as yields fall. Health-care stocks were under pressure after a Federal judge ruled that Obamacare unconstitutional. All 30 Dow components finished the day in the red, led by a 4.5% loss for American Express Co. AXP, -0.59% , while all 11 sectors of the S&P 500 wrapped up in negative territory. The Nasdaq's losses erased all of its year-to-date gains and currently stands down 2.2% for 2018 thus far. The Fed concludes its rate-setting meeting on Wednesday at 2 p.m. Eastern Time.