here's the info from Wikipedia. They are an S&L, whatever that means. For all intents and purposes they are a bank.
http://en.wikipedia.org/wiki/Washington_MutualThey are also FDIC insured.
From Wikipedia:
The most important purpose of these institutions is to make mortgage loans on residential property. These organizations, which also are known as savings associations, building and loan associations, cooperative banks (in New England), and homestead associations (in Louisiana), are the primary source of financial assistance to a large segment of American homeowners. As home-financing institutions, they give primary attention to single-family residences and are equipped to make loans in this area.
Some of the most important characteristics of a savings and loan association are:
1. It is generally a locally owned and privately managed home financing institution.
2. It receives individuals' savings and uses these funds to make long-term amortized loans to home purchasers.
3. It makes loans for the construction, purchase, repair, or refinancing of houses.
4. It is state or federally chartered.