Powayseller,
Vanguard’s CA tax exempt Money Market does not contain any MBSs or Agency securities (Freddie Mac, Fannie Mae et.al). I checked with Vanguard on their exposure to real estate. They mentioned that 17.36% of their funds are invested in private ..(something).. bonds (bonds issued by CA govt to build private assets like stadiums). But they are still debt instruments that the CA govt is liable for. So I think they have the same risk exposure as the T-bills from treasury direct.
