After attempting a third positive day in a row, the S&P and Nasdaq vomited within the last hour of trading, amid news that President Trump will be giving a news conference Friday regarding China.

The Dow Jones Industrial Average which had traded over 210 points higher on the day, plummeted to close down 150 points, or 0.58%. The S&P 500 was up on the day as well before closing off by 0.21% while the Nasdaq Composite lost 0.46%.

 rump’s announcement followed a decision by China’s National People’s Congress to ratify a national security bill for Hong Kong. The bill will sidestep Hong Kong’s legislature, elevating concerns over the longevity of Hong Kong’s “one party, two systems” concept that permits more freedoms mainland China is missing.

“If the HK response involves broad sanctions against individuals or entities, that would be a larger issue and not something the SPX could easily dismiss,” said Adam Crisafulli of Vital Knowledge, in a note. Stock valuations are “too high in general and leave no room for error while investors aren’t paying enough attention to rising US-China tensions.”

In addition to the news of the press conference, technical indicators suggest stocks may be due for a significant selloff as well.

Despite a move higher earlier in the session, the NYSE’s Arms Index, also known as The Trading Index (TRIN), indicates now that market internals are showing signs of panic selling, suggesting investors may be looking to sell on the day’s rally. The TRIN is a breadth oscillator that aids in the measurement of internal market strength or weakness.

The number of stocks climbing on the big board outnumbered decliners by a ratio of 1.24 to 1, but volume in declining stocks is leading advancers by a 1.77-to-1 ratio. That drove the Arms Index to 2.195, the highest reading since it reached 2.486 on March 3, when the Dow dropped 786 points or 2.9% and the S&P 500 plummeted 2.8%.

While earlier in the day there was optimism related to reopening the economy and positive economic data, there is still uncertainty as to how consumers will react, and how the market will recover.

“The greatest stimulus for the economy is a safe reopening,” wrote Gregory Faranello, head of U.S. rates trading at AmeriVet Securities. “In the end, reopening in and of itself will gradually show improvement although the true demand-side still remains unclear.”

Stock Index ETFs followed moves in the benchmark stock indexes, with the SPDR S&P 500 ETF Trust (SPY), the SPDR Dow Jones Industrial Average ETF (DIA), and the Invesco QQQ Trust (QQQ), all sinking into the close.

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