The Bank of Japan said it will conduct an unlimited bond purchase operation to prevent yields climbing further, as investors put pressure on its yield curve target.

The BoJ will buy unlimited quantities of 10-year government bonds at a “purchasing yield” of 0.25% on February 14. The central bank’s yield curve control policy aims to keep the 10-year yield at 0%, with a tolerance of plus or minus 25 basis points.

The past month has seen yields climb steadily, as investors increase bets that the