Arch Mortgage Insurance Company (Arch MI) | 15,236 followers on LinkedIn. Arch Mortgage Insurance (“Arch MI”) is a leading provider of private mortgage insurance (MI) in the United States. Backed by a solid capital base, we offer expert risk management and financial services to help mortgage lenders protect their investments and expand their origination opportunities. We expand homeownership by making it possible for eligible borrowers to buy a house with only modest down payments.