Goldman Sachs Research discusses the scope of JPY intervention.

The MOF apparently conducted another round of intervention on May 6, possibly around the same size as the first one on April 30 and similarly against broader macro pressures. While the MOF still has plenty of capacity to conduct subsequent rounds of intervention with roughly $1.1tn left of cash and securities combined, we do not see a compelling case to significantly deplete reserves in the current backdrop," GS notes.

"First, if the MoF were to shift to selling Treasuries, it would put further upward pressure on US yields and arguably prove self-defeating. Second, and in a similar vein, as long as the currency is prevented from weakening in line with fundamentals, the lever of adjustment will fall on JGBs," GS adds.