JP Morgan strategists warn that a break of USD/JPY above 155 could trigger
concentrated short covering and accelerate yen appreciation. They estimate 16–17
trillion yen (about $102.6 billion) of yen short positions remain open and say,
in theory, full covering of those positions could push USD/JPY down to the
142–146 range. Recent price action appears consistent with a still-large short
position base, raising the risk of larger-than-expected yen strength.