NEW YORK (Reuters) - The euro fell below $1.10 on Friday to its weakest since May 2017 as a multi-day downward shift in the single currency intensified in afternoon trade.

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Traders had varied explanations for the drop, including that month-end rebalancing of portfolios heightened an existing bias. The longer-term trend, which has seen the euro fall 0.90% in August, has been driven by an economic slowdown in Europe among other factors.

“We had a quick 50-odd point drop, which seems to be month-end related. Clearly the euro has been quite soft for some time. We touched below $1.10 earlier in August and we’ve struggled really to rebound from that point. The underlying softness that we’ve seen persist in the past month seems very much intact,” said Shaun Osborne, chief foreign exchange strategist at Scotia Capital.

The move also began shortly after President Donald Trump tweeted that the euro was dropping “like crazy” and lamented the state of the U.S. dollar, attributing its strength to Federal Reserve policy. A weaker dollar would send the euro higher, suggesting the tweet did not have a direct effect on the pair. The euro was last trading at $1.0976 against the dollar, down 0.71% on the day.

Poor euro zone economic data on Thursday reinforced views that the European Central Bank would cut its benchmark interest rate and announce a new round of quantitative easing at its September meeting. Christine Lagarde, the ECB’s next president, said the central bank still has room to cut rates if necessary, though divisions remain within the ECB.

“There still seems to be a debate in the ECB if there will be a significant burst of easing or a more measured move next month,” said Osborne.

At the September meeting, “we think rate cuts at least, though it may not be the time for renewed QE.”

As the dollar rose, the offshore Chinese yuan headed toward its biggest monthly decline in 25 years as the two countries prepared for the implementation of new retaliatory tariffs on Sunday.

The dollar index was 0.38% higher at 98.884, closing the month little moved after having been whipped around by trade headlines. Against the dollar, the offshore yuan was 0.28% weaker at 7.163, set for a 3.69% fall in August, it’s biggest monthly drop since 1994.

An additional 5% tariff on $125 billion of goods from China is slated to kick in on Sunday. Investors fear the intensifying trade dispute could lead the U.S. economy into recession.