On the first trading day of April, which is also the first trading day of the second quarter, stocks tanked thanks to a combination of anxiety about a trade war, and fears about the tech industry getting hit with regulation.

The Dow Jones industrial average plunged 458.92 points to close at 23,644.19, with Intel as the worst-performing stock in the index. The 30-stock index fell as much as 758.59 points and hit a new low for the year on Monday, falling at one point below the intraday low touched during the slide in February.

The dropped 2.2 percent to 2,581.88 and re-entered correction territory, with tech falling 2.5 percent. The index also closed below its 200-day moving average, a key technical level, for the first time since June 2016. The Nasdaq composite dropped 2.7 percent to 6,870.12 as Amazon declined 5.2 percent.

The Nasdaq closed in correction territory for the first time.

"The market leaders are under pressure," said Marc Chaikin, CEO of Chaikin Analytics. "It's a situation where the proven winners for the past few years are faltering." When that happens, "there is a negative psychological sense in the market."

Amazon fell after President Donald Trump tweeted on Saturday that Amazon was scamming the U.S. Postal Service, adding the service loses "billions of dollars" delivering packages for the e-commerce giant. Amazon has been one of the best-performing stocks over the past year, rising nearly 64 percent in that time period.

Facebook, Netflix and Alphabet also closed sharply lower, dropping 2.8 percent, 5.1 percent and 2.4 percent, respectively. Last month, concerns over how Facebook handles data collected from its users sent the entire sector lower. Facebook dropped 10.4 percent in March.