In a case that has shocked crisis-hit Spain, the executives at Spain's Caja Madrid and Bankia group face possible charges of embezzlement and disloyal administration over allegations that they spent €15.5 million ($17.6 million) on nightclubs, safaris and other luxuries using secret company credit cards.
In his ruling, the judge said it was now important to establish on what grounds the cards had been issued.
He said there were serious doubts about the expenses incurred using the credit cards in question.
Among those linked to the probe is former IMF boss Rodrigo Rato.
Rato chaired savings bank Caja Madrid before it was merged with others in 2010 to form Bankia, the group whose near-collapse sparked a €41 billion ($52-billion) bailout for Spain's financial sector and caused thousands of customers to lose their savings.
Rato was expelled from Spain's ruling Popular Party when the scandal broke.