Having slumped to 9,420.85 on Feb. 6, the 225-issue Nikkei average has been hovering around 12,000 in recent days.
The rally was fueled by the government's antideflation package -- and its move to tighten controls on short sales in particular.
The package reflects the government's determination to forestall a March crisis, which many had feared would arise from stock price falls causing unrest within the financial system.