The dollar fell against the euro and jumped against the Japanese yen on Thursday as investors focused on month-end rebalancing of their portfolios.

The euro bounced and the yen fell sharply just before forex rates were set for the month at the end of the London session.

“It looks flow-driven,” said Erik Nelson, a macro strategist at Wells Fargo in New York, especially as other markets including bank stocks and euro zone bonds didn’t see similar moves. “Nothing has even come close to the move we’ve seen in the euro.”

The euro jumped 0.77% to $1.0957, the highest since April 15. The dollar gained 0.53% against the yen to 107.27.

The cross-currency basis swap for swapping three-month yen LIBOR for dollar LIBOR also turned negative for the first time in a month, indicating strong demand for dollars against the Japanese currency for the end of the month.

The dollar had gained against the euro earlier on Thursday as stocks slipped and after the European Central Bank disappointed some investors who had expected that it would expand bond purchases to junk bonds as part of its quantitative easing program.

It was “a combination of weaker risk and short-term reaction to the ECB announcement that there would be no QE expansion,” said Vassili Serebriakov, an FX strategist at UBS in New York.

The dollar index against a basket of currencies rose to 99.73 after the ECB meeting, before falling back to 98.99, down 0.50% on the day.

The greenback has weakened from more than a three-year peak of 102.99 in late March as global central banks launched massive stimulus measures to protect economies from the coronavirus outbreak.

The Federal Reserve on Wednesday kept interest rates near zero and promised to expand emergency programs as needed to help the battered U.S. economy.

Improving risk appetite, if it continues, could dent the dollar further. Investors are more optimistic that economies globally are closer to reopening.

“If we are seeing a bit of a rebound in risk, and I would say the last week or so has been quite encouraging on that front, then that would suggest that this would take some of the upward pressure off the dollar,” said Craig Erlam, senior market analyst at OANDA in London.