As the effects of official currency market intervention begin to fade, a senior strategist at Bank of New York Mellon has turned to a staple of Japanese fast food to gauge the true extent of the yen's weakness. Geoff Yu created the Curry Cutlet Index as an alternative to The Economist's Big Mac Index, arguing that comparing the international price of curry and cutlet rice offers a more accurate reflection of how the yen's depreciation impacts Japanese consumers.

On Wednesday morning in global forex markets, the dollar was trading around ¥159.23. However, according to Yu's calculations, considering the purchasing power of the yen as reflected in the price of curry meals, the dollar should be valued at just ¥62.18. This suggests the foreign exchange market is significantly undervaluing the yen. In comparison, the Big Mac Index, which compares the price of McDonald's burgers across countries, indicates that the dollar should be worth around ¥80.30.

Yu noted that if the goal is to align purchasing power with high-income nations, this index shows the yen needs to be much stronger. His calculations are based on the prices of CoCo Ichibanya, the world's largest curry rice restaurant chain, which operates around 1,500 locations globally.