Cal. Ins. Code § 4097.20

If the name of a mutual insurer converting to a stock insurer pursuant to this article includes the word “mutual,” the new stock insurer may continue to use the word “mutual” in its name if the name includes a word or words that identify the new stock insurer as a stock insurer and the commissioner finds that the continued use of the word “mutual” in its name is not likely to mislead or deceive the public.