The yen gained 0.5% on Wednesday, extending its advance this month to about 4%, while the Bloomberg Dollar Spot Index fell as much as 0.2% toward its weakest level since Feb. 18. The move renewed scrutiny of yen-funded carry trades, as a stronger Japanese currency raises the cost of repaying yen-denominated borrowing used to finance higher-yielding assets. Markets are also awaiting the US Treasury’s announcement of the size of an expanded buyback of outstanding 10- to 20-year securities, a program linked in market coverage to a 20% Bitcoin surge after Bitcoin returned to $80,000 in August from months near $60,000. Treasury Secretary Scott Bessent challenged traders betting against the yen and said he had asymmetric information and substantial insight into Japanese policy. Estimates for the initial buyback range from $5 billion to $6 billion to nearly $8 billion, compared with an initially stated minimum of $4 billion. Friday’s US inflation data and the Federal Reserve’s policy meeting next week remain central risks for the dollar-yen outlook, with money markets assigning about a 60% probability of a quarter-point rate increase.