Shares in troubled Spanish lender Bankia S.A. are plunging on Madrid's Ibex 35 index in the first day of trading after the bank announced it will need 19 billion euros ($23.84 billion) in state aid.

Bankia's shares fell 28 percent to 1.13 euros after opening Monday. They were at 1.57 euros before trading was suspended Friday.

The bank is estimated to have 32 billion euros in toxic assets following the collapse of Spain's real estate sector in 2008. The bailout, requested by Bankia' s board late Friday, is Spain's biggest.

The interest rate for Spain's benchmark 10-year bond, an indicator of investor wariness, was at 6.33 percent, up 4 basis points from Friday.

Spain fears the cost of rescuing its banks could overwhelm its finances and force it to seek European help.