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Fractional real estate ownership financing takes two forms: Traditional Timeshare and Larger Share Fractional Ownership
Fractional mortgages for shares of 1/26 ownership or 2 weeks or less are considered timeshare financing, and is often provided initially by the project developers. Larger shares of ownership is generally considered fractional ownership and is typically in shares of 1/2, 1/4, 1/6, 1/8, 1/10, 1/12, 1/20.
Fractional financing is more difficult for most lenders since there is a small market for these loans, and no established secondary market for vacation finance mortgages of these types. Several companies make loans for fractional homes, yachts, planes and other properties.
Source of the article : Wikipedia