The yen, weakened by the Japanese government's easy monetary policy, hit a 38-year low against the US dollar on Wednesday, sparking speculation about a new intervention by authorities.

Stocks were mostly lower despite a tech rebound that helped the Nasdaq edge into positive territory.

The yen slid as far as 160.75 to the greenback.

Despite sliding through the 160 level, there was no indication that authorities had intervened to support the yen, said market analyst David Morrison at Trade Nation.

"This being the case, it's possible that traders work to push the yen lower in a renewed attempt to test the resolve of the Japanese authorities," he said.

Japan's top currency official has said authorities were ready to act 24 hours a day if the unit fell too far, but some investors suspect that the new trigger may be 165 yen to the dollar.

Billions were pumped in to support the yen after it hit a 34-year low of 160.17 in late April, but with limited effect. (AFP)