The Japanese yen has already erased half the gains that came from the historic US-Japan currency intervention, raising questions over the efficacy of the maneuver and whether more currency moves may be needed to stop the yen’s slide. It’s “going to take more” to create a sustained upswing, a Russell Investments strategist told the FT in reference to the yen, which was trading around 164 per dollar last month before jumping to 155 after the joint action. It’s now at 159 and traders are “skeptical we can see a much stronger yen unless it’s followed up by stronger policy action,” a Pioneer Investments strategist told Bloomberg, with investors now pegging the probability that Bank of Japan hikes interest rates at 50%.