The yen carried on its seemingly inevitable decline toward ¥150 per dollar, as traders scoured intraday moves for evidence of subtle intervention from Japan.

Twice in under a week investors have seen sudden bursts of yen strength as it edged to fresh lows, spurring speculation that officials are subtly intervening to support the currency. The yen traded around the ¥149.30 level Wednesday, after weakening to ¥149.38 on Tuesday in a volatile session which included such a spike.

"The move seems to have been driven off of electronic flows rather than ‘voice’ driven flows which points to ‘stealth’ intervention,” Brad Bechtel, global head of foreign exchange at Jefferies, wrote in an Tuesday note. "Maybe they are warming up to defend ¥150.00 as the next big psychological level above.”