The fragile economy makes worrying almost an official job responsibility for the governor of the Bank of Japan. Looking back on six weeks at the helm of the central bank, Gov. Toshihiko Fukui even worried about worrying.

"As I rushed to and fro in the past month, I wondered if we weren't in danger of losing sight of the essence of economic policy by paying too much attention to stock price falls right before us," Fukui said in an interview Thursday. "This tendency poses a grave risk to the whole of Japan."

The threat to banks from recent stock price plunges to 20-year lows prompted the BOJ to ease its monetary policy Wednesday. But Fukui was quick to quell hopes of stock-price-keeping operations by the BOJ.