Shares in Spain's largest rescued lender Bankia plummeted on Monday when they started trading after a revaluation at the end of last week as part of a bailout deal with the European Union.
The shares, which closed at 0.25 euro on Friday, dropped as much as 52 percent shortly after trading began. They recovered to trade about 23 percent lower by around 1000 GMT.
Spain's bank restructuring fund had valued the shares at 1 euro cent on Friday. The new valuation was imposed by the European Union as Bankia prepares to get a capital injection of 10.7 billion euros from European rescue funds.
Last year, Bankia became Spain's biggest-ever bank failure. The state had to nationalize the bank and apply to Europe for a 41 billion euro rescue for Bankia and others that held hundreds of billions of euros in bad debt from the country's property market crash in 2008.
Bankia was created from a merger of seven savings banks in 2011. When the bank listed, some 350,000 Spaniards bought shares, which were worth 3.75 euros at that time.
On Monday, the shares began trading more than an hour after the market opened because demand could not match supply.
Also on Monday, credit ratings agency Standard and Poor's downgraded Bankia to BB- from BB and its parent company BFA to B- from B. It removed these ratings from negative outlook.