The dollar has tumbled to its weakest level in almost two months, a move amplified by a sharp rally in the yen that reverberated across global currency markets.

The Bloomberg Dollar Spot Index kept ticking lower Thursday after slumping as much as 0.4% on Wednesday to its lowest level since late May. The Japanese currency broke through ¥156 to the greenback in Tokyo trading on Thursday morning, amid ongoing speculation authorities could intervene again to prop it up.

The yen has surged about 4% since July 11, when Japan is thought to have waded into the market with a surprise bout of buying. The currency was boosted the following day by another suspected intervention, and more recently by a prominent Japanese minister calling on the central bank to increase interest rates to boost the value of the currency, and former U.S. President Donald Trump flagging the exchange rate’s weakness.