In the New York market on the 18th, the yen temporarily fell to the ¥158 range, but rebounded sharply shortly afterward, recovering to the upper ¥156 range. Speculation spread in the market that the BOJ had conducted a rate check, heightening concern over yen-buying intervention.
In the New York foreign exchange market on the 18th, the yen was at one point sold down to around ¥158 per dollar. It was then rapidly bought back, rising to the upper ¥156 range.
Speculation spread in the market that the BOJ had conducted a "rate check," in which it asks private-sector banks about current exchange-rate levels. This was seen as a factor pushing the yen back up.