MADRID — Standard & Poor’s slashed its ratings on the creditworthiness of five Spanish banks on Friday, just as one of them — Bankia, the nation’s largest real estate lender — requested an additional 19 billion euros in rescue funds from the country, far beyond initial government estimates.


Earlier Friday, the Spanish stock market regulator suspended trading in Bankia shares amid expectations that the nationalized bank would be asking for more money. Bankia already had been granted a 4.5 billion euro emergency loan from Spain.


Bankia, battered by its exposure to the collapse of Spanish real estate market, also will be restating its 2011 results to show a big loss.


Bankia, formed in a seven-way merger in 2010, was meant to be the government’s flagship project to consolidate the savings banks, or cajas. Instead, its forced rescue has prompted broader concerns among investors about whether Spain can still finance alone the rescue of such banks. As a result, some analysts are warning that the outflow of money from Spain — so far relatively limited and led by foreign investors — could turn into a full-fledged bank run.


After Greece, Spain is now in the cross hairs of the three-year-old European debt crisis. The European Commission recently forecast Spain would be the only euro economy in recession next year.


Three of the five Spanish banks downgraded by S.& P. on Friday — Bankia, Bankinter and Banco Popular Español — were knocked down to junk status, while the two others — Banco Financiero y de Ahorros and Banca Cívica — were not. The rating agency also kept the ratings of nine other Spanish banks the same, but said the outlook for all of them was negative.