"WaMu was incorporated as the Washington National Building Loan and Investment Association on September 25, 1889
In November 1994, WaMu formed a new holding called Washington Mutual, Inc. and separated its non-banking units from its primary banking unit, Washington Mutual Savings Bank, which was simultaneously renamed Washington Mutual Bank."
I don't trust anything Wikipedia, since history often get's re-written there, however....the above is what it says. Not sure there's any relevance at all., but it does imply WMI had a parent that created it.