Japan's central bank shed more of its bond stockpile in a single year than it ever has before. The Bank of Japan's holdings of Japanese Government Bonds (debt the national government issues to fund its spending, commonly abbreviated as JGBs) fell by 47.8 trillion yen compared with the same month a year earlier. July's reading is the largest annual decline the Bank of Japan has recorded in its bond holdings.
Central banks accumulate government bonds by buying them in the open market, a tool that pushes money into the financial system and holds borrowing costs down. When those holdings shrink, the bank has either sold bonds outright or allowed them to mature without buying new ones to replace them. The Bank of Japan built its JGB stockpile through years of such purchases.
The 47.8 trillion yen figure is a year-over-year comparison. It measures the difference between July of this year and July of the prior year, not a single month's transaction. The Bank of Japan's bond book was that much smaller in July than it had been twelve months before.
No prior year-over-year reading matched this size.