The government wants to limit the assets in the bad bank to 90 billion euros ($116.6 billion). Bankia said Wednesday that it was hoping to transfer bad property loans valued at 24.6 billion euros ($31.9 billion), a discount of 27.9 percent compared with their current book value.

The International Monetary Fund also highlighted the difficulties in setting up the bad bank during a correction in the housing market. In a report issued Wednesday about Spain’s finance sector, the fund said that future transactions by the bad bank could “become reference prices for the market, given low turnover in the housing market.” After a prolonged recession, the I.M.F. predicted, Spain’s economy would grow 1 percent in 2014.

Caixabank, one of Spain’s largest institutions, is set to acquire Banco de Valencia, one of the four rescued banks, for a symbolic euro. Banco de Valencia is expected to receive 4.5 billion euros ($5.8 billion) of the European bailout money approved Wednesday.

Of the four rescued banks, Banco de Valencia was the only one for which Brussels reached the conclusion that “the bank’s viability could not be restored on a stand-alone basis.” The commission, which is the executive arm of the European Union, said the other three banks had the potential to rebound once their balance sheets were cleaned. By 2017, the balance sheet of each bank will be reduced by more than 60 percent compared to 2010, the commission forecast.

The conditions set by Europe are intended to ensure that the bailout does not distort competition in the banking sector. Mr. Almunia said the restructuring plans presented by the four banks were “very serious and very demanding.”

“I very much hope that the results that we expect to obtain from these decisions will allow the taxpayers — in this case the euro area countries’ taxpayers who are also taking risks, not only the Spanish taxpayers — to get an adequate return for these efforts,” he said.