TOKYO, Jan 29 (Reuters) - The yen tumbled, the Nikkei stock index soared and Japanese government bond yields sank to record lows on Friday, after the Bank of Japan eased monetary policy, saying it will adopt negative interest rates.
The dollar was up 1.5 percent at 121.478 yen, on track to post its biggest intraday gain since December 2014. The greenback had soared more than 2 percent at one point to touch 121.495, its highest since Dec. 18.
The Nikkei index was up 1.8 percent, and the benchmark 10-year Japanese government bond yield dropped to a record low of 0.185 percent.
The BOJ on Friday eased monetary policy further, implementing a negative 0.1 percent interest rate for excess reserves for financial institutions. (Reporting by the Tokyo markets team; Editing by Jacqueline Wong)