美联储部分住房所有权：定量分析

Partial Homeownership: A Quantitative Analysis

Authors: Eirik Eylands Brandsaas and Jens Kvaerner

Abstract

A convex combination of renting and traditional homeownership—Partial Ownership (PO)—is becoming increasingly popular. This paper incorporates an existing for-profit PO contract into a life-cycle model to analyze its impact on housing investment, household welfare, and financial stability. Key findings include:

1. Increased Housing Investment: PO makes more households invest in housing.
2. Willingness to Pay: Willingness to pay for PO increases with housing unaffordability, particularly among low-income and renting households.
3. Financial Stability: Despite raising aggregate debt, PO may reduce systemic risk by shifting the most indebted traditional homeowners to partial ownership.

Introduction

The decision to rent or buy a home is one of the most significant financial choices. Over the past decade, house prices have doubled in many cities, raising concerns about housing affordability and economic growth. Financial innovations like PO can help promote homeownership, offering flexibility in housing choices. PO allows households to buy a fraction of a home and rent the remainder. It differs from timeshare agreements, which are more common in vacation destinations. PO is now used in several countries, including Norway, Sweden, England, Australia, and China.

Model and Data

The study uses a life-cycle model of housing, incorporating a for-profit PO contract. The model accounts for household differences in wealth, education, and income risk. Data are sourced from administrative records in Norway and proprietary partial ownership data.

Impact of PO

• Short-term Impact: In the short term, PO leads to a reduction in rental households as they switch to PO. Among households aged 25 to 45, about 25% were renters, which dropped to 12.5% after PO became available.
• Long-term Impact: In the long run, PO decreases traditional homeownership. The model predicts that 20% of young households become partial homeowners, aligning with survey data showing the hypothetical demand for PO.
• Willingness to Pay (WTP): The mean welfare gain from having access to PO ranges from 19% to 4% of disposable income for households aged 25 to 45. Renters have a significantly higher WTP for PO than owners, with a 35-year-old renter willing to pay 33% of disposable income compared to 4% for owners.

Financial Stability

• Debt-to-Income Ratio (DTI): As many renters borrow to become partial owners, the DTI ratio in the population rises. However, wealthier households prefer PO and borrow less.
• Downsizing: PO has little impact on downsizing along the extensive margin but leads to a 50% decrease in the housing value lost among downsizers. This reduces the right tail of the DTI distribution and lowers the value of downsizing after adverse shocks.

Conclusion

Introducing PO in a life-cycle model of housing requires a new utility parameter called ownership-elasticity, which measures the proportion of homeownership utility relative to ownership share. The study finds that households owning 50% of a home receive 85% of the utility premium associated with full homeownership. The high take-up rates among young households suggest that PO could reshape housing markets and promote more flexible ownership structures.