On Wednesday and Thursday, comments from Trump as well as Treasury Secretary Steven Mnuchin and Commerce Secretary Wilbur Ross contributed to swings in stock prices and the dollar as investors tried to parse the remarks for indications of administration's stances on the dollar and global trade.
Friday's losses came despite signs that the USA may have entered a period of stronger economic growth.
In the past, though, Trump has said he prefers a weaker dollar to help US trade.
Now this looks like Trump's comments have turned it around. Following the original comment, the USA dollar sank to a three-year low on Wednesday.
"Foreigners will not fund USA debt if the policy of the United States is to degrade the stability of the dollar", Bove, of the Vertical Group, said in a report.
Investors were struck by Mnuchin's comments because for most of the past two decades, U.S. Treasury chiefs regularly stated that a "strong dollar is in the best interests of the United States".
This was not the first time Trump seemed to support a weaker dollar.More news: Wynn's Incredibly Tone Deaf Response to Sexual Harassment and Assault Allegations
More news: Tourists face jail for 'porn dance' antics in Cambodia
More news: Air Power One wants new fridges - and it's going to price $24M
The Commerce Department said the US economy grew 2.6 percent in the fourth quarter.
Economist Lawrence Summers wrote an op-ed in the Washington Post, saying Mnuchin "fails on style and substance". The currency fell to its lowest level in over three years as a result, forcing the Trump official to clarify his position.
'The market forces, fundamentals all suggest that the dollar should weaken over the course of 2018, ' said Roy Teo, investment strategist for LGT Bank in Singapore. "And again, in terms of the benefits, it is beneficial for our trade imbalances", he said.
Johnson named mining company Freeport-McMoRan as his pick for the metals stock for reaping the rewards of a lower US dollar.
"It's a very, very liquid market, and we believe in free currencies", Mnuchin said, adding: "There're both advantages and disadvantages on where the dollar is in the short term".
Sterling rose 0.4 percent to $1.4191, but remained well below its peak on Thursday of $1.4346, which was the pound's highest level since the Brexit vote in June 2016 as some investors turned bullish on the currency's outlook.
The has been in a year-long decline, defying forecasts that it should strengthen from the fact that the Federal Reserve is raising interest rates and normalizing monetary policy faster than its counterparts.