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Social Connectedness in Urban Areas

Coauthors: Michael Bailey, Patrick Farrell, and Theresa Kuchler

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Wired

Daily Mail

Slate

We use anonymized and aggregated data from Facebook to explore the spatial structure of social networks in the New York metro area. We highlight the importance of transportation infrastructure in shaping urban social networks by showing that travel time and travel costs are substantially stronger predictors of social connectedness between zip codes than geographic distance is. We also document significant heterogeneity in the geographic breadth of social networks across New York zip codes, and show that much of this heterogeneity is explained by the ease of access to public transit, even after controlling for socioeconomic characteristics of the zip codes' residents. When we group zip codes with strong social ties into hypothetical communities using an agglomerative clustering algorithm, we find that geographically non-contiguous locations are grouped into socially connected communities, again highlighting that geographic distance is an imperfect proxy for urban social connectedness. We also explore the social connections between New York zip codes and foreign countries, and highlight how these are related to past migration movements.

Peer Effects in Product Adoption

Coauthors: Michael Bailey, Drew Johnston, Theresa Kuchler and Arlene Wong

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LSE Business Review

We study the nature of peer effects in the market for new cell phones. Our analysis builds on de-identified data from Facebook that combine information on social networks with information on users' cell phone models. To identify peer effects, we use variation in friends' new phone acquisitions resulting from random phone losses and carrier-specific contract terms. A new phone purchase by a friend has a substantial positive and long-term effect on an individual's own demand for phones of the same brand, most of which is concentrated on the particular model purchased by the friend. We provide evidence that social learning contributes substantially to the observed peer effects. While peer effects increase the overall demand for cell phones, a friend's purchase of a new phone of a particular brand can reduce individuals' own demand for phones from competing brands---in particular those running on a different operating system. We discuss the implications of these findings for the nature of firm competition. We also find that stronger peer effects are exerted by more price-sensitive individuals. This positive correlation suggests that the elasticity of aggregate demand is substantially larger than the elasticity of individual demand. Through this channel, peer effects reduce firms' markups and, in many models, contribute to higher consumer surplus and more efficient resource allocation.

Five Facts about Beliefs and Portfolios

Coauthors: Stefano Giglio, Matteo Maggiori, and Stephen Utkus

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NBER Digest

WSJ

We administer a newly-designed survey to a large panel of retail investors who have substantial wealth invested in financial markets. The survey elicits beliefs that are crucial for macroeconomics and finance, and matches respondents with administrative data on their portfolio composition and their trading activity. We establish five facts in this data: (1) Beliefs are reflected in portfolio allocations. The sensitivity of portfolios to beliefs is small on average, but varies significantly with investor wealth, attention, trading frequency, and confidence. (2) It is hard to predict when investors trade, but conditional on trading, belief changes affect both the direction and the magnitude of trades. (3) Beliefs are mostly characterized by large and persistent individual heterogeneity; demographic characteristics explain only a small part of why some individuals are optimistic and some are pessimistic. (4) Investors who expect higher cash flow growth also expect higher returns and lower long-term price-dividend ratios. (5) Expected returns and the subjective probability of rare disasters are negatively related, both within and across investors. These five facts challenge the rational expectation framework for macro-finance, and provide important guidance for the design of behavioral models.

Climate Change and Long-Run Discount Rates: Evidence from Real Estate

Revision requested at the Journal of Political Economy

Coauthors: Stefano Giglio, Matteo Maggiori, Krishna Rao, and Andreas Weber

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VoxEU

Global Risk Institute

Climate Risk Conference

The optimal investment to mitigate climate change crucially depends on the discount rate used to evaluate the investment's uncertain future benefits. The appropriate discount rate is a function of the horizon over which these benefits accrue and the riskiness of the investment. In this paper, we estimate the term structure of discount rates for an important risky asset class, real estate, up to the very long horizons relevant for investments in climate change abatement. We show that this term structure is steeply downward-sloping, reaching 2.6% at horizons beyond 100 years. We explore the implications of these new data within both a general asset pricing framework that decomposes risks and returns by horizon and a structural model calibrated to match a variety of asset classes. Our analysis demonstrates that applying average rates of return that are observed for traded assets to investments in climate change abatement is misleading. We also show that the discount rates for investments in climate change abatement that reduce aggregate risk, as in disaster-risk models, are bounded above by our estimated term structure for risky housing, and should be below 2.6% for long-run benefits. This upper bound rules out many discount rates suggested in the literature and used by policymakers. Our framework also distinguishes between the various mechanisms the environmental literature has proposed for generating downward-sloping discount rates.

Published or Forthcoming Papers

Segmented Housing Search

Forthcoming at the American Economic Review

Coauthors: Monika Piazzesi and Martin Schneider

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We study housing markets with multiple segments searched by heterogeneous clienteles. In the San Francisco Bay Area, search activity and inventory covary negatively across cities, but positively across market segments within cities. A quantitative search model shows how the endogenous flow of broad searchers to high-inventory segments within their search ranges induces a positive relationship between inventory and search activity across segments with a large common clientele. The prevalence of broad searchers shapes the response of housing markets to localized supply and demand shocks. Broad searchers help spread shocks across many segments and reduce their effect on local market activity.

Hedging Climate Change News

Forthcoming at the Review of Financial Studies

Coauthors: Robert Engle, Stefano Giglio, Bryan Kelly, and Heebum Lee

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Climate Risk Data

NYU Summary

Harvard Law School

Climate Risk Conference

We propose and implement a procedure to dynamically hedge climate change risk. To create our hedge target, we extract innovations in climate news series that we construct through textual analysis of high-dimensional data on newspaper coverage of climate change. We then use a mimicking-portfolio approach to build climate change hedge portfolios using a large panel of equity returns. We discipline the exercise by using third-party ESG scores of firms to model their climate risk exposures. We show that this approach yields parsimonious and industry-balanced portfolios that perform well in hedging innovations in climate news both in sample and out of sample. The resulting hedge portfolios outperform alternative hedging strategies based primarily on industry tilts. We discuss multiple directions for future research on financial approaches to managing climate risk.

House Price Beliefs and Mortgage Leverage Choice

Forthcoming at the Review of Economic Studies

Coauthors: Michael Bailey, Eduardo Davila and Theresa Kuchler

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We study the relationship between homebuyers' beliefs about future house price changes and their mortgage leverage choices. Whether more pessimistic homebuyers choose higher or lower leverage depends on their willingness and ability to reduce the size of their housing market investments. When households primarily maximize the levered return of their property investments, more pessimistic homebuyers reduce their leverage to purchase smaller houses. On the other hand, when considerations such as family size pin down the desired property size, pessimistic homebuyers reduce their financial exposure to the housing market by making smaller downpayments to buy similarly-sized homes. To determine which scenario better describes the data, we investigate the cross-sectional relationship between house price beliefs and mortgage leverage choices in the U.S. housing market. We use plausibly exogenous variation in house price beliefs to show that more pessimistic homebuyers make smaller downpayments and choose higher leverage, in particular in states where default costs are relatively low, as well as during periods when house prices are expected to fall on average. Our results highlight the important role of heterogeneous beliefs in explaining households' financial decisions.

House Prices, Local Demand, and Retail Prices

Journal of Political Economy, 127(3), June 2019

Coauthor: Joseph Vavra

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[WP Version]

VoxEU

Citylab

We use detailed micro data to document a causal response of local retail price to changes in house prices, with elasticities of 15%-20% across housing booms and busts. Notably, these price responses are largest in zip codes with many homeowners, and non-existent in zip codes with mostly renters. We provide evidence that these retail price responses are driven by changes in markups rather than by changes in local costs. We then argue that markups rise with house prices, particularly in high homeownership locations, because greater housing wealth reduces homeowners' demand elasticity, and firms raise markups in response. Consistent with this explanation, shopping data confirms that house price changes have opposite effects on the price sensitivity of homeowners and renters. Our evidence has implications for monetary, labor and urban economics, and suggests a new source of markup variation in business cycle models.

The Economic Effects of Social Networks: Evidence from the Housing Market

Journal of Political Economy, 126(6), December 2018

Coauthors: Michael Bailey, Ruiqing Cao and Theresa Kuchler

Winner Glucksman Institute Research Prize, 2017

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[WP Version]

Appendix

NBER Digest

The Conversation

LSE Business Review

Media Coverage:

CNBC

Citylab

Inman News

We show how data from online social networking services can help researchers better understand the effects of social interactions on economic decision making. We use anonymized data from Facebook, the world's largest online social network, to first explore heterogeneity in the structure of individuals' social networks. We then exploit the rich variation in the data to analyze the effects of social interactions on housing market investments. To do this, we combine the social network information with housing transaction data. Variation in the geographic dispersion of social networks, combined with time-varying regional house price changes, induces heterogeneity in the house price experiences of different individuals' friends. We show that individuals whose geographically distant friends experienced larger recent house price increases are more likely to transition from renting to owning. They also buy larger houses and pay more for a given house. Similarly, when homeowners' friends experience less positive house price changes, these homeowners are more likely to become renters, and more likely to sell their property at a lower price. We find that these relationships are driven by the effect of social interactions on individuals' housing market expectations. Survey data show that individuals whose geographically distant friends experienced larger recent house price increases consider local property a more attractive investment, with bigger effects for individuals who regularly discuss such investments with their friends.

Social Connectedness: Measurement, Determinants, and Effects

Journal of Economic Perspectives, 32(3), Summer 2018

Coauthors: Michael Bailey, Ruiqing Cao, Theresa Kuchler and Arlene Wong

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[WP Version]

Appendix

SCI Data

Public Health Post

VoxEU

F8 Talk

Media Coverage:

New York Times

Economist

AEA

Marginal Revolution

Bloomberg

We introduce a new measure of social connectedness between U.S. county pairs, as well as between U.S. counties and foreign countries. Our measure, which we call the Social Connectedness Index (SCI), is based on the number of friendship links on Facebook, the world's largest online social network. Within the U.S., social connectedness is strongly decreasing in geographic distance between counties. The population of counties with more geographically-dispersed social networks is richer, more educated, and has higher life expectancy. Region-pairs that are more socially connected have higher trade flows, even after controlling for geographic distance and the similarity of regions along other demographic and socioeconomic measures. Higher social connectedness is also associated with more cross-county migration and patent citations. Social connectedness between U.S. counties and foreign countries is correlated with past migration patterns, with social connectedness decaying in the time since the primary migration wave from that country. Trade with foreign countries is also strongly related to the social connectedness with those countries. These results suggest that the SCI captures an important role of social networks in facilitating economic and social interactions. Our findings highlight the potential for the SCI to mitigate the measurement challenges that pervade empirical literatures that study the role of social interactions across the social sciences.

Do Banks Pass Through Credit Expansions to Consumers Who Want to Borrow?

Quarterly Journal of Economics, 133(1), February 2018

Coauthors: Sumit Agarwal, Souphala Chomsisengphet and Neale Mahoney

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[WP Version]

Appendix

Slides

NBER Digest

VoxEU

Chicago Booth

Media Coverage:

Economist

Financial Times

Bloomberg

FT Podcast

STLAR Interview

We propose a new approach to studying the pass-through of credit expansion policies that focuses on frictions, such as asymmetric information, that arise in the interaction between banks and borrowers. We decompose the effect of changes in banks' shadow cost of funds on aggregate borrowing into the product of banks' marginal propensity to lend (MPL) to borrowers and those borrowers' marginal propensity to borrow (MPB), aggregated over all borrowers in the economy. We apply our framework by estimating heterogeneous MPBs and MPLs in the U.S. credit card market. Using panel data on 8.5 million credit cards and 743 credit limit regression discontinuities, we find that the MPB is declining in credit score, falling from 59% for consumers with FICO scores below 660 to essentially zero for consumers with FICO scores above 740. We use a simple model of optimal credit limits to show that a bank's MPL depends on a small number of "sufficient statistics" that capture forces such as asymmetric information, and that can be estimated using our credit limit discontinuities. For the lowest FICO score consumers, higher credit limits sharply reduce profits from lending, limiting banks' optimal MPL to these consumers. The negative correlation between MPB and MPL reduces the impact of changes in banks' cost of funds on aggregate household borrowing, and highlights the importance of frictions in bank-borrower interactions for understanding the pass-through of credit expansions.

Asymmetric Information about Collateral Values

Journal of Finance, 71(2), June 2016

Winner Brattle Group Prize, First Prize, 2016

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[WP Version]

Appendix

VoxEU

I empirically analyze credit market outcomes when competing lenders are differentially informed about the expected return from making a loan. I study the residential mortgage market where property developers often cooperate with vertically integrated mortgage lenders to offer financing to buyers of new homes. I show that these integrated lenders have superior information about the construction quality of individual homes and exploit this information to lend against higher-quality collateral, decreasing foreclosures by up to 40%. To compensate for this adverse selection on collateral values, non-integrated lenders charge higher interest rates when competing against a better-informed integrated lender.

Government Intervention in the Housing Market - Who Wins, Who Loses?

Journal of Monetary Economics, 80, June 2016

Coauthors: Max Floetotto and Michael Kirker

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[WP Version]

Appendix

Many U.S. government policies aim to encourage homeownership. We use a general equilibrium model with heterogeneous agents to consider the effects of temporary homebuyer tax credits and the asymmetric tax treatment of owner-occupied and rental housing on prices, quantities, allocations, and welfare. The model suggests that homebuyer tax credits temporarily raise house prices and transaction volumes, but have negative effects on welfare. Removing the asymmetric tax treatment of owner-occupied and rental housing can generate welfare gains for a majority of agents across steady states, but welfare impacts are substantially more varied along the transitions between steady states.

No-Bubble Condition: Model-Free Tests in Housing Markets

Econometrica, 84(3), May 2016

Coauthors: Stefano Giglio and Matteo Maggiori

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[WP Version]

Appendix

VoxEU

We test for the existence of housing bubbles associated with a failure of the transversality condition that requires the present value of payments occurring infinitely far in the future to be zero. The most prominent such bubble is the classic rational bubble. We study housing markets in the U.K. and Singapore, where residential property ownership takes the form of either leaseholds or freeholds. Leaseholds are finite-maturity, pre-paid, and tradable ownership contracts with maturities often exceeding 700 years. Freeholds are infinite-maturity ownership contracts. The price difference between leaseholds with extremely-long maturities and freeholds reflects the present value of a claim to the freehold after leasehold expiry, and is thus a direct empirical measure of the transversality condition. We estimate this price difference, and find no evidence for failures of the transversality condition in housing markets in the U.K. and Singapore, even during periods when a sizeable bubble was regularly thought to be present.

Testing for Information Asymmetries in Real Estate Markets

Review of Financial Studies, 28(4), August 2015

Coauthor: Pablo Kurlat

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[WP Version]

Appendix

In housing markets, neighborhood characteristics are a key source of information heterogeneity: sellers are usually better informed about neighborhood values than buyers are, but some sellers and buyers are better informed than their peers are. Consistent with predictions from a new framework for analyzing such markets with heterogeneous assets and differentially informed agents, we find that changes in the composition of sellers toward more informed sellers and sellers with a larger supply elasticity predict subsequent house price declines. This effect is larger for houses with more price exposure to neighborhood characteristics, and smaller for houses bought by buyers that are more informed.

Very Long-Run Discount Rates

Quarterly Journal of Economics, 130(1), February 2015 (Lead Article)

Coauthors: Stefano Giglio and Matteo Maggiori

Winner Jacob Gold & Associates Best Paper Prize, ASU Sonoran Winter Finance Conference, 2014

Winner Glucksman Institute Research Prize, 2015

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[WP Version]

Appendix

Data Summary

Data Sets

VoxEU

NBER Digest

Media Coverage:

Forbes

Economist [1]

Economist [2]

National Review

CBS News

Business Spectator

We estimate how households trade off immediate costs and uncertain future benefits that occur in the very long run, 100 or more years away. We exploit a unique feature of housing markets in the U.K. and Singapore, where residential property ownership takes the form of either leaseholds or freeholds. Leaseholds are temporary, pre-paid, and tradable ownership contracts with maturities between 99 and 999 years, while freeholds are perpetual ownership contracts. The price difference between leaseholds and freeholds reflects the present value of perpetual rental income starting at leasehold expiry, and is thus informative about very long-run discount rates. We estimate the price discounts for varying leasehold maturities compared to freeholds and extremely long-run leaseholds via hedonic regressions using proprietary datasets of the universe of transactions in each country. Households discount very long-run cash flows at low rates, assigning high present value to cash flows hundreds of years in the future. For example, 100-year leaseholds are valued at more than 10% less than otherwise identical freeholds, implying discount rates below 2.6% for 100-year claims.

Regulating Consumer Financial Products: Evidence from Credit Cards

Quarterly Journal of Economics, 130(1), February 2015

Coauthors: Sumit Agarwal, Souphala Chomsisengphet and Neale Mahoney

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[WP Version]

Appendix

NBER Digest

Micro Insights

Media Coverage:

NY Times

Businessweek

Bloomberg

Washington Post

Slate

Yahoo

US News

Vox

We analyze the effectiveness of consumer financial regulation by considering the 2009 Credit Card Accountability Responsibility and Disclosure (CARD) Act. We use a panel data set covering 160 million credit card accounts and a difference-in-differences research design that compares changes in outcomes over time for consumer credit cards, which were subject to the regulations, to changes for small business credit cards, which the law did not cover. We estimate that regulatory limits on credit card fees reduced overall borrowing costs by an annualized 1.6% of average daily balances, with a decline of more than 5.3% for consumers with FICO scores below 660. We find no evidence of an offsetting increase in interest charges or a reduction in the volume of credit. Taken together, we estimate that the CARD Act saved consumers $11.9 billion per year. We also analyze a nudge that disclosed the interest savings from paying off balances in 36 months rather than making minimum payments. We detect a small increase in the share of accounts making the 36-month payment value but no evidence of a change in overall payments.

A Simple Framework for Estimating Consumer Benefits from Regulating Hidden Fees

Journal of Legal Studies , 43(S2), June 2014

Coauthors: Sumit Agarwal, Souphala Chomsisengphet and Neale Mahoney

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[WP Version]

Policymakers are increasingly turning to regulation to reduce hidden or non-salient fees. Yet the overall consumer benefits from these polices are uncertain because firms may increase other prices to offset lost fee revenue. We show that the extent to which firms offset reduced hidden fee revenue is determined by a simple equation that combines two "sufficient statistics," which can be estimated or calibrated in a wide range of settings: (i) a parameter that captures the degree of market competitiveness and (ii) a parameter that captures the salience of the hidden fee. We provide corroborating evidence for this approach by drawing upon evidence on the effect of fee regulation under the 2009 CARD Act. We also illustrate the applicability of our approach by using the framework to assess a hypothetical regulation of airline baggage fees.

Resource Extraction Contracts Under Threat of Expropriation: Theory and Evidence

Review of Economics and Statistics , 95(5), December 2013

Coauthor: Arthur van Benthem

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[WP Version]

VoxEU

Knowledge@Wharton

We use fiscal data on 2,468 oil extraction agreements in 38 countries to study tax contracts between resource-rich countries and independent oil companies. We analyze why expropriations occur and what determines the degree of oil price exposure of host countries. With asymmetric information about a country's expropriation cost even optimal contracts feature expropriations. Near-linearity in the oil price of real-world hydrocarbon contracts also helps to explain expropriations. We show theoretically and verify empirically that oil price insurance provided by tax contracts is increasing in a country's cost of expropriation, and decreasing in its production expertise. The timing of actual expropriations is consistent with our model.

Estimated Impact of the Fed's Mortgage-Backed Securities Purchase Program

International Journal of Central Banking , 8(2), June 2012

Coauthor: John B. Taylor

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VoxEU

The largest credit or liquidity program created by the Federal Reserve during the financial crisis was the mortgage-backed securities (MBS) purchase program. In this paper, we examine the quantitative impact of this program on mortgage interest rate spreads. This is more difficult than frequently perceived because of simultaneous changes in prepayment risk and default risk. Our empirical results attribute a sizeable portion of the decline in mortgage rates to such risks and a relatively small and uncertain portion to the program. For specifications where the existence or announcement of the program appears to have lowered spreads, we find no separate effect of the stock of MBS purchased by the Fed.