Stocks extended their declines on Monday and were on track to close with their worst losses of the year as investors grew nervous over a White House immigration ban.

The S&P 500 was down 1%, and the Nasdaq declined 1.4%. The Dow Jones Industrial Average fell 1%, retreating to below 20,000 again. The blue-chip index had hit that milestone for the first time last week.

Donald Trump late Friday signed an executive order temporarily banning immigration from seven Muslim-majority countries, including Iran and Iraq. The hasty rollout led to widespread confusion over whether the ban extended to green card holders, leaving a number of permanent residents stranded in U.S. airports.

Federal judges in New York and Virginia, among others, overruled the ban on visa holders. Thousands also flooded to airports across the country, including John F. Kennedy International Airport in New York and Dulles International Airport in Virginia, to protest the immigration order.

A number of American companies, particularly those in Silicon Valley, voiced disappointment in the White House's executive order. Netflix (NFLX) - Get Report , Apple (AAPL) - Get Report , Facebook (FB) - Get Report and Microsoft (MSFT) - Get Report were among those that expressed concern. Apple CEO Tim Cook issued a letter stating that, "Apple would not exist without immigration, let alone thrive and innovate the way we do."

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The president has had a rocky first week in office, regularly facing public backlash over a number of his actions. Among his first moves in the White House, Trump and his team railed against the media, called into question the legitimacy of voting systems, and disputed photo evidence that his inaugural crowds were smaller than the inauguration of former President Barack Obama.

"The maelstrom our president has unleashed over immigration, and the seven countries under temporary ban, is yet another reason to honor our models' cautionary stance in the near-term," said Raymond James' Jeffrey Saut in a note. "Our country is amazingly dynamic and the equity markets are only impacted by such events in the short-term. Longer-term we remain convinced the equity markets are in a secular bull market that has years left to run."

Airlines and other travel stocks moved lower on the immigration ban. JetBlue (JBLU) - Get Report , Southwest Airlines (LUV) - Get Report , American Airlines (AAL) - Get Report , Delta Air Lines (DAL) - Get Report and Spirit Airlines (SAVE) - Get Report sank, while Priceline (PCLN) , Tripadvisor (TRIP) - Get Report , Expedia (EXPE) - Get Report and Ctrip (CTRP) - Get Report logged losses.

Personal income and spending in the U.S. both rose in December, according to the Bureau of Economic Analysis. Incomes rose 0.3% in December, slightly below 0.4% consensus but three times the pace in November. Spending increased 0.5%, in-line with estimates.

Pending home sales moved higher in December as demand continued to drive strength in the housing market. Pending sales, wherein a contract has been signed but a deal not yet closed, rose 1.6% in December. The increase was far higher than expected 0.6% growth.

Tempur Sealy (TPX) - Get Report plummeted 28% after Mattress Firm said its contracts with the mattress and bedding company would be terminated. Tempur Sealy and Mattress Firm were unable to agree on a number of changes to existing agreements. Tempur Sealy CEO Scott Thompson said it was in the company's "long-term interest of all our stakeholders" to terminate the contracts.

Fitbit (FIT) - Get Report declined 13% after cutting its fourth-quarter outlook. The fitness tracker company expects an adjusted loss of 51 cents to 56 cents a share, far worse than previous profit guidance of 14 cents to 18 cents a share. Fitbit also announced plans to cut 110 jobs, or 6% of its workforce, in an effort to reduce expenses. The moves are in response to a slowdown in the wearables market.

Rite Aid (RAD) - Get Report was slammed 16% after agreeing with Walgreens Boots Alliance (WBA) - Get Report to lower its acquisition price to $6.50 to $7 a share, depending on divestitures tied to regulatory approval. A Rite Aid acquisition was originally priced at $9 a share when the deal was announced in October 2015.

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Booz Allen Hamilton (BAH) - Get Report reported a rise in revenue over its third quarter, though profit declined. The government consulting company reported adjusted earnings of 38 cents a share, down from 41 cents and missing estimates by 2 cents. Revenue increased more than 7% to $1.4 billion, exceeding forecasts of $1.37 billion.