The dollar weakened and the yen hit its highest level in more than a year on Monday, as market participants increasingly expected an oversized rate cut by the Federal Reserve later this week. The dollar fell to as low as 139.

The US dollar is entering a downward trend as the Federal Reserve starts lowering borrowing costs and signs of optimism emerge in other parts of the world, according to Sophia Drossos, a strategist and economist at Point72 Asset Management.

The U.S. dollar has been sliding in the run-up to a widely expected interest-rate cut from the Federal Reserve on Wednesday and, depending on the size of the Fed’s move, it could end up weakening further — or it may be a buying opportunity.