The Barcelona-based firm stopped operating on Friday and more than 200 flights were abruptly cancelled.
The Spanish government is taking legal action and said Spanair could be fined 9m euros (£7.6m; $11.9m) over the collapse.
In 2010, Spanair reported an operating loss of 115m euros.
The collapse comes after Qatar Airways stopped takeover talks, ending the prospect of further financing, and also reflects weak demand for air travel in Spain.
In 2008 a Spanair plane was involved in Spain's worst aviation disaster in 25 years, when it crashed on takeoff as it tried to leave Madrid's Barajas airport, killing 154 people. The aircraft's wing flaps were incorrectly positioned and a warning system failed to alert the pilots.
The airline was seen as a flagship of the regional government of Catalonia, which had helped it stay afloat with more than 150m euros of subsidies.