The failure to contain radiation risk from the crippled nuclear power plant in Fukushima Prefecture, and the resulting turmoil in stocks, threaten to worsen damage to the economy from last week's earthquake and tsunami.

The Nikkei 225 stock average fell 16 percent in the first two days of this week, the steepest tumble since 1987. Although the stock benchmark rebounded Wednesday by 5.68 percent to 9,093.72, its future prospects remain uncertain.

Bank of America-Merrill Lynch on Tuesday further cut its forecasts for gross domestic product, which shrank last quarter, and JPMorgan Chase & Co. may do the same.