Core Viewpoint - The statement by U.S. Treasury Secretary Yellen has weakened the last psychological defense of the yen, leading to a reduction in intervention expectations and making shorting the yen a more attractive trade [1][10]. Group 1: Market Reactions - Following Yellen's statement on January 28, the USD/JPY pair rebounded sharply from around 152.7 to 153.8, erasing losses caused by rumors of a "New York Fed price check" [1]. - The market's focus has shifted from intervention speculation to the fundamental strength of Japan's economy [5][10]. Group 2: Intervention Expectations - Yellen's denial of intervention has diminished the perceived "policy risk premium" associated with USD/JPY, making shorting the yen more appealing [3]. - There is insufficient evidence to suggest that Japan has intervened in the currency market, as data from the Bank of Japan shows no significant yen-buying activity during recent declines [4]. Group 3: Fundamental Factors - The market is now assessing three key areas regarding Japan's fundamentals: fiscal policy, inflation expectations, and monetary policy [5]. - The upcoming elections and the lack of clarity on funding for tax cuts could create downward pressure on the yen if fiscal expansion continues without a clear financing plan [5]. - Rising domestic inflation expectations have been found to correlate with a weaker yen, indicating that even without widening interest rate differentials, the yen remains under pressure [6]. Group 4: Monetary Policy Implications - Short-term, Yellen's comments may reduce expectations for immediate rate hikes by the Bank of Japan, but if USD/JPY approaches the 150 level again, the Bank may find it challenging to maintain its current stance [8]. - The weakening of the yen is becoming a significant variable in the Bank of Japan's response function, potentially leading to increased rate hike expectations if the yen depreciates too quickly [8][9].