Bank of America Global Research on the key 155 level in USD/JPY post the US-Japan joint intervention.

"We believe a break below ¥155 could trigger a meaningful shift in market dynamics. If ¥155 holds, market participants are likely to continue viewing it as a floor and may re-establish short-yen positions. Conversely, a sustained move below ¥155 could trigger stop-loss selling in USD/JPY," BofA notes.

"In addition, the latest BOJ Tankan survey showed that Japanese corporates are assuming USD/JPY levels in the ¥152s for the current fiscal year. It is reasonable to infer that ¥150 and ¥155 are among the most widely used planning assumptions. Given the strengthening consensus for yen weakness this year, hedge ratios may have declined. A break below ¥155 could therefore encourage corporate hedgers to shift toward selling USD/JPY on rallies rather than sitting on USD/JPY carry," BofA adds.