Japan’s benchmark bond yield hit the maximum allowed by the central bank Friday. The Bank of Japan [doubled a cap](https://www.wsj.com/articles/bank-of-japan-remains-only-major-central-bank-with-ultra-low-rates-11671506532?mod=article_inline) on 10-year yields on Dec. 20, allowing them to go as high as 0.5%. Bond yields rise when prices fall. The move surprised market participants, and sent yields rapidly higher—but the new limit wasn’t tested until Friday. The Bank of Japan has stuck to its ult
