As a candidate, Trump campaigned on an "America First" trade policy, and a big fear for investors has been that increasingly nationalistic governments will impose barriers that hurt the global economy and trade, as well as profits for US exporters.
The SPI had been looking at a fall of 33 points just before Trump's announcement just after 5 am Sydney time, this then surged to a fall of 61 points, or more than 1% at the close. The Nasdaq fell 92 points, or 1.3 percent, to 7,180.
The Dow Jones industrial average sank 380 points, or 1.5 percent, to 25,029.
The Fed's chairman, Jerome Powell, jolted markets on Tuesday, when he said that he's feeling more optimistic about the US economy.
Earlier in the week, Powell's testimony helped send Treasury yields jumping and stocks tumbling when he said that he's feeling more optimistic about the economy. His address to congress signalled the Fed will keep raising interest rates to contain inflation.
Markets in South Korea and Thailand were closed for holidays on Thursday.
Industrial companies like Boeing and Caterpillar that use steel and aluminum fell sharply, as did exporters like Apple whose overseas sales could be hurt by a trade war.
Shares of steelmakers swung wildly amid speculation that the USA government would impose tariffs or quotas on steel and aluminum imports. The Nasdaq composite was up 10 points, or 0.1 percent, to 7,283.
The index lost 3.9 percent in February.
This also lifted the yield for U.S. 10 year government bonds, a global benchmark for commercial lending, past a four-year high of 2.92 per cent.
The S&P 500 index finished down1.3% at 2,677, falling beneath a psychologically significant level at 2,678. Visit MarketWatch.com for more information on this news. It was down as much as 10 percent earlier.
Stocks flipped between modest losses and gains Thursday as Powell told a Senate committee that the central bank continues to plan a gradual rise in interest rates.
BUSY ECONOMIC DAY: A raft of reports on the economy provided a mixed picture. It had only four such days a year ago.
Other reports showed that manufacturing is growing at its fastest rate in almost 14 years, while construction spending was weaker than economists expected last month.
The biggest loss in the S&P 500 came from Foot Locker, which plunged after it said sales trends were weaker last quarter than analysts expected.
In the commodities markets, benchmark USA crude rose 26 cents to settle at $61.25 per barrel. Brent crude, the worldwide standard, lost 62 cents to $64.11 per barrel.
The dollar dipped to 106.24from 106.66 yen late Wednesday. The euro rose to $1.2331 from $1.2255, and the British pound rose to $1.3790 from $1.3768.
OVERSEAS: France's CAC 40 fell 1.1 percent and Germany's DAX was down 2 percent. London's FTSE 100 was down 0.7% in afternoon trade. In Asia, Japan's Nikkei 225 lost 1.6 percent and Hong Kong's Hang Seng rose 0.6 percent.
Israeli police have already recommended indicting Netanyahu for bribery, fraud and breach of trust in two separate cases. Netanyahu is in Washington D.C to take part in the annual AIPAC conference where he is scheduled to speak on Tuesday.
OSCAR BRAYNON: We're talking about a bill that is going to, in my opinion, put people, children in my community in harm's way. In coordination with a few local organizations, some are planning a local March For Our Lives .
The new law will be presented to the Council of Ministers - France's equivalent of a cabinet - later this month. Ms Schiappa told AFP news agency that her ministry was "very glad" that the higher age was chosen.
Sharma started the third round solidly with three birdies in the first six holes but was a mediocre one-over the rest of the way. For a player who is almost five years removed from his last victory (2013 Open Championship) the confidence has returned.
He also earned defensive MVP honors in the Peach Bowl in January, which capped UCF's undefeated season with a win over Auburn. Shaquille now plays for the Seattle Seahawks . "I think I beat that by a lot", Griffin told reporters at the combine.
The notice also advised USA citizens in Turkey should avoid large crowds, keep a low profile and otherwise be cautious. Starting March 5, the Embassy will provide "only emergency services", the Monday announcement said.
If you get defensive or you back off at all against players like you've got this week, then you've got no chance of winning". The highlight was a near-ace at the 17th, his eighth hole of the day - where his tee shot spun within inches of the cup.
White House trade adviser Peter Navarro said Sunday that Trump is not planning to exempt any countries from the tariff hike. The American International Automobile Dealers Association quickly issued a statement against the plan.
The two are in love and planning for the future but after celebrating Marina's birthday one evening, Orlando falls seriously ill. With special thanks to Adam David Rohe for his advisement on aspects of this article .
Nintendo Switch Play Data Reset to get Fix in Future Update
In a statement to GameSpot, the company said, "Some Nintendo Switch owners' play activity information is displaying incorrectly". Now we're taking a look at Bayonetta 2 on the Wii U and Nintendo's current flagship console - the Switch.
IEA: US to dominate the oil industry
Iran's light crude oil price rose $2.43 in the week ended on February 23 to settle at $62.39 per barrel, IRNA reported on Sunday. Exports will more than double over the next six years to 4.9 million barrels a day, according to the IEA's estimates.
Senate debates gun, school-safety bill
The state senate initially passed the measure on a voice vote, but the body reconsidered the amendment and voted to overturn it. But much of the debate Saturday revolved around gun control and whether people should have a right to own an assault rifle.
Meghalaya also goes to NDA, Conard Sangma to be CM
Instead, it said it is talking to "like-minded people". "But there are circumstances and so we will have to be here", he said. But the designated Chief Minister said: "It is not about the single largest but it is about the group who has the majority".
NK rejects talks with United States 'under preconditions'
North Korea, whose official name is the Democratic People's Republic of Korea, has repeatedly described the drills as a threat. North Korea reiterated on Saturday that it was willing to talk to the USA but said it would never sit with any precondition.