President-elect Donald Trump's shock comment that the dollar is too strong suggests the U.S. is about to declare as dead a two-decade policy of publicly favoring a strong currency. "There's no question that the Trump administration would not want a strong dollar. A strong dollar does nothing good for whatever Trump is basically trying to do," said David Woo, Bank of America Merrill Lynch's head of global rates and foreign exchange research. "Yes, the U.S. fundamental story is bullish for the U.S. dollar, but the problem here is they actually don't want a strong dollar. I think it's going to go up. However, it's going to be a much more volatile climb." Trump's remarks also took a shot at one of the most crowded trades on the planet — long wagers on the dollar. That trade has been a bet that Trump's policies will reflate the economy, causing interest rates and the greenback to rise. But that dollar move is at odds with building a more powerful American manufacturing base, because a strong dollar makes exports more expensive for foreign buyers. The dollar also threatens the economic health of emerging-market nations, as the cost of everything there rises, including servicing their dollar-denominated debt.

This is the first time we have a president-elect say the dollar has gone too far. He's saying things and doing things that no president has ever done before. Marc Chandler chief foreign exchange strategist, Brown Brothers Harriman

The dollar index gained as much as 6 percent after the election but began retreating in early January and is now up only about 3 percent since Nov. 8. The dollar index was down about 0.7 percent Tuesday on Trump's comment and on pressure from the pound and euro. British sterling rose about 2.7 percent after Prime Minister Theresa May laid out the government's plans for negotiating its exit from the European Union and said Parliament would have to vote on the deal. The euro also rose.

Trump made his comment in an interview in The Wall Street Journal, where he said the so-called border-adjustment tax proposed by Congress is too complicated to enact. That tax is part of a proposed corporate tax overhaul and would tax imported goods at the border at a proposed 20 percent. Some economists say the dollar could rise sharply in response, by as much as 25 percent. "This is the first time we have a president-elect say the dollar has gone too far," said Marc Chandler, chief foreign exchange strategist at Brown Brothers Harriman. "He's saying things and doing things that no president has ever done before." Presidents in recent history have refrained from talking the currency up or down, and Chandler says going back to Clinton Treasury Secretary Robert Rubin, the policy has been for a strong dollar. Even when the dollar's strength created headwinds, administrations have stood by it, at least verbally. Trump said the dollar was already "too strong," and he pointed a finger at the Chinese currency. "Our companies can't compete with them now because our currency is too strong. And it's killing us," he told the newspaper. Trump said the yuan has been "dropping like a rock," and that recent Chinese moves to support its currency were done "because they don't want us to get angry."

Chandler said the yuan is at a two-month high. It's the fourth week in a row that the dollar has fallen against the yuan. He said the dollar was down 0.75 percent Tuesday against the yuan, which stood at 6.8491 per dollar.

"It raises questions. Are we back to Lloyd Bentsen? He talked the dollar down and the dollar collapsed. Is this a jettison of the Rubin strong dollar policy? We don't know," said Chandler. Treasury Secretary Jack Lew, in office for just a few more days, was asked on CNBC about Trump's strong dollar comment. "I think what we've seen over the last couple of years is a U.S. economy that has been on a relative basis stronger than other countries around the world. That has naturally led to a stronger dollar," said Lew. Events over the weekend and on Tuesday make the confirmation hearing of Trump's nominee for Treasury secretary, Steven Mnuchin, all the more interesting on Thursday. Woo said he does not expect Mnuchin to tout the strong dollar policy. Instead, he expects him to stop short of it as he did in a recent CNBC interview by more or less saying a strong "economy" is in the best interest of the U.S. That is very like the comment made by Lew on Tuesday.

I think they're now actually intervening to protect their currency, not drive it down. Treasury Secretary Jack Lew on the Chinese yuan

Lew also said China has made positive strides. "We pushed them to refrain from doing anything on their currency that would lead people to think they're manipulating," he said. "I think they're now actually intervening to protect their currency, not drive it down." Robert Sinche, chief global strategist at Amherst Pierpont, said in a note that Trump's comment seems to have been aimed at China, but it has been taken more generally about the value of the greenback. In a note, Sinche said there appear to be differences among incoming advisors in the Trump administration, but it's "probably safe to say that reiteration of the "strong USD policy" is unlikely to be a regular comment by US officials in the years ahead." Trump's comments, made Friday, came four days ahead of President Xi Jingping's speech at the World Economic Forum in Davos, Switzerland, where he discussed globalization and warned against protectionism on Tuesday. Xi is the first Chinese president to speak at Davos, which acts as a conclave for globalists from all over the world. "Pursuing protectionism is like locking yourself in a dark room, which would seem to escape the wind and rain, but also block out the sunshine and air," Xi said. "Waging a trade war will only cause injury and loss to both sides."

We don't know how much credence to give it. Some people take him literally. Should people take him literally? The Chinese don't know. Marc Chandler chief foreign exchange strategist, Brown Brothers Harriman