Regulators seized five banks in Florida, Missouri, New Mexico, Oregon and Washington, lifting the total number of failures this year to nine as financial institutions struggle with loan defaults and a weak economy.

Two of the five institutions had assets of more than $1 billion. The Florida bank, in Miami, was sold to an investment group that includes former North Fork Bancorp Chief Financial Officer Dan Healy. The deposits and assets of the New Mexico bank went to Texas billionaire Andrew Beal.

The...