These guys insure the banks against their mortgage losses. They are the safety, security and SOLVENCY firewall.
In 1991 Rhode Island had it's own little bank failure nightmare when all the credit unions in the state failed simultaneously.
The links below are 2 short articles from the NYT from those days.
http://query.nytimes.com/gst/fullpage.html?res=9D0CE3DF153FF937A35752C0A967958260http://query.nytimes.com/gst/fullpage.html?res=9D0CE7D8163FF937A35752C0A967958260&sec=&spon=&pagewanted=allIt wasn't the credit unions that failed, it was the INSURER of the credit unions, RISDIC (Rhode Island Share Indemnity Corporation) that failed, when they could not cover the losses of one rinky dink Rhode Island credit union embezzler - revealing that the whole "insured deposits" meme was an illusion - causing a run on the credit unions, and THEN causing a subsequent failure.
They closed the credit unions on New Years Day 1991. In one day, the Rhode Island economy was turned into a moonscape.
People lost homes, businesses, money. For real. They were denied access to THEIR money. It went on forever. It drove Rhode Island into a depression that I don't believe it ever pulled out of.
That's why when I read about private mortgage insurance being in trouble, I am ALARMED. When I read about the insurers of municiple bonds being in trouble, I am ALARMED.