THEMA

Carlos SERRANO - HEC PARIS

2025-12-16T08:46:58Z

“Acquiring Patents in Secret : Disclosure Timing in Markets for Technology."
(George Chondrakis, Carlos Serrano, Rosemarie Ziedonis)

Abstract : Markets for technology provide a vibrant channel through which firms purchase ownership rights to patented inventions. Although such transactions enable firms to secure access to intangible assets originating beyond their borders, they also provide cues to competitors regarding the purchasing firm's technological investments. This study explores the timing of strategic disclosure of patent acquisitions and the conditions under which firms trade the benefits of competitor deterrence through early recordation for those of secrecy through delayed disclosure. Using evidence on the lag between the execution and recording dates for US patents purchased by publicly traded corporations, we predict and find earlier disclosure of patent acquisitions when the buyer works on related technologies and is better positioned to enforce the patents (i.e., is large and relatively litigious). As predicted by the model, we also find that the buyer delays disclosure when the seller is a large firm, suggesting that buyers take advantage of the seller's ability to deter competitors while keeping the transaction secret. Additional analyses reveal that (a) regulatory changes reducing the value of keeping acquisitions of patent applications secret lead to shorter recording lags, and (b) increases in the enforceability of business method and software patents further accelerate the voluntary recording of patent ownership changes. The study provides new evidence on the tradeoffs that innovating firms face when determining the timing of disclosure for patents they have purchased in technology markets.

Graziella BERTOCCHI - UNIVERSITA DI MODENA E REGGIO EMILIA

ygustave — 2025-12-08T09:51:43Z

"Family Planning and Ethnic Heritage : Evidence from Sub-Saharan Africa"
with Arcangelo Dimico and Chiara Falco

Abstract :
Using ethnographic, ecological, and folklore data for sub-Saharan Africa, we investigate the role played by postpartum sexual abstinence, an extensively documented practice that in preindustrial societies finds its biological justification as a means to safeguard child survival. We show that the duration of contemporary postpartum abstinence increases with that of ancestral postpartum sex taboos within a woman's ethnic group ; raises fertility ; lengthens birth intervals though not sufficiently to meet recommended guidelines ; is detrimental for children's health ; is associated with lower age at first birth and female disempowerment ; and is adopted
as a purification ritual, out of respect of ancestral traditions.

Sylvain CARRE - UNIVERSITE PARIS I PANTHEON SORBONNE

ygustave — 2025-12-01T08:41:03Z

"Efficiency in DeFi Lending : Interest Rate Mechanisms and Liquid Staking"
joint work with Franck Gabriel)

Abstract : Liquid staking, a notable recent innovation in decentralized finance (DeFi) allows to delegate and redeploy capital which was traditionally locked and has thus been promoted for its “capital efficiency” virtues. In the context of DeFi lending, we build a tractable general equilibrium model to analyze two strategic interactions between investors, which, we show, affect the performance of liquid vs traditional staking. We find that without a proper adjustment of the DeFi lending interest rate mechanism, liquid staking can worsen efficiency even when there are no delegation costs. When the interest rate is optimally set, a combination of mild delegation costs and limited investor competition can lead to the same conclusion.

Alexandre DE CORNIERE - TOULOUSE SCHOOL OF ECONOMICS

ygustave — 2025-11-24T07:17:17Z

"Seller-Side Tying of Platform Services, joint with Kinshuk Jerath and Greg Taylor"

Abstract :
This paper analyzes the practice of seller-side tying in digital platforms, where access to a core intermediation service is conditioned on the seller using ancillary services such as fulfillment or payment processing. We develop a model in which a monopoly platform intermediates transactions between consumers and competing sellers, and can choose whether to force the sellers to tie a costly ancillary service to the core offering. Consumers value the ancillary service heterogeneously, and seller adoption decisions generate vertical differentiation that affects market prices and consumer platform participation. We show that tying resolves under-adoption of the ancillary service, increases competition between sellers, and raises consumer surplus. In contrast, a ban on tying or a structural separation of the platform reduces service adoption and harms consumers. These results differ from consumer-side tying where, in our setting, bundling the core and ancillary services is neither profitable for the platform nor beneficial to consumers. The efficiency rationale for seller-side tying is robust under multiple variations of our main model.

Gabrielle FACK - DAUPHINE UNIVERSITY- PSL

ygustave — 2025-11-17T07:54:30Z

« The Effects of Affirmative Action on Targeted and Non-Targeted Students : Evidence from Low-Income Priorities in Paris High Schools »
Gabrielle Fack (Université Paris Dauphine-PSL), Julien Grenet (Paris School of Economics), YingHua He (Rice University)

Ylenia BRILLI - CA FOSCARI UNIVERSITY OF VENICE

ygustave — 2025-10-30T13:03:00Z

"How raising the full retirement age affects women's early retirement choices : insights from the interaction of two policies"
with Elena Bassoli, ETH Zurich

Abstract :

This paper analyzes how a reform increasing statutory retirement age from 60 to 64 affected women's incentives for early retirement. In Italy, women can anticipate retirement at 57 (with 35 contribution years), but subject to an annuity penalization. Using Italian administrative data, we compare women eligible for the early retirement scheme before and after the reform, finding a small effect on women's retirement age, but a substantial negative effect on annuity. Effects are stronger for women with low labor market attachment or working full-time, suggesting that reconciliation of paid and unpaid works is an important driver of early retirement choices.

Christian HILBER - THE LONDON SCHOOL OF ECONOMICS AND POLITICAL SCIENCE

lcollin — 2025-10-29T10:27:15Z

"Structural Density and Homeownership"

Abstract :

One of the most salient stylized facts about homeownership is that multifamily units—typically located in more central parts of cities—are much less likely to be owner-occupied than single-family units. This fact is consistent with landlord production efficiency advantages associated with structural density, arising from economies of scale and coordination frictions. To derive testable predictions and guide our empirical analysis, we develop a simple modified monocentric city model that incorporates these efficiency advantages and spatial variation in structural density due to centrality and soil conditions. To identify the causal effect of structural density, and to disentangle it from other determinants of homeownership, we employ a novel instrumental variable (IV) strategy derived from the engineering literature, exploiting differences in soil quality. Using data at the ward level in England and grid level in Germany, our IV-estimates show that a ten–percentage-point increase in the share of multifamily housing reduces the local homeownership rate by about eight to nine percentage points. The magnitude of this effect aligns with observed spatial differences in homeownership within England and Germany (in-sample) and across Europe (out-of-sample). In England, about half of the effect reflects sorting, whereas in Germany sorting appears negligible. We provide direct evidence for our proposed mechanism and confirm our findings using an alternative empirical strategy based on a large European household panel.« »

Natacha RAFFIN - ENS PARIS SACLAY

ygustave — 2025-10-20T08:41:24Z

"New fertility patterns : The role of human versus physical capital"

Abstract :
We use an overlapping generations model with physical and human capital, and two reproductive periods to explore how fertility decisions may differ in response to economic incentives in early and late adulthood. In particular, we analyze the interplay between fertility choices—related to career opportunities—and wages, and investigate the role played by work experience and investment in both types of capital. We show that young adults postpone parenthood above a certain wage threshold and that late fertility increases with human capital. The long run trend is either to converge to a low productivity equilibrium, involving high early fertility, investment in physical capital and relatively low income, or to a high productivity equilibrium, where households postpone parenthood to invest in their human capital and work experience, with higher late fertility and higher levels of income. A convergence to the latest state would explain the postponement of parenthood and the mitigation or slight reversal of fertility decrease in some European countries in recent decades.

Emmanuel HANSEN - LUDWIG MAXIMILIANS UNIVERSITAT MUNCHEN

ygustave — 2025-10-13T08:22:07Z

"Self-Financing Tax Cuts Around the World : New Theoretical Results and Applications"

Abstract :
This paper studies whether tax-transfer systems are inefficient in the sense of allowing for self-financing tax cuts. In the first part, we combine household micro data from representative surveys with tax-transfer calculators for 33 countries around the world. We show that, with standard labor supply elasticities, self-financing tax cuts exist for all 29 countries in which the effective marginal tax rates (EMTR) exhibit sudden drops. In the second part, we show analytically that sudden drops in EMTRs give rise to inefficiencies whenever (a) taxpayers are rational and have additively separable preferences, or (b) taxpayers use the ironing heuristic and EMTRs are above some threshold. In the third part, we characterize discrete tax reforms that bring inefficient tax-transfer systems to the Pareto frontier. For this purpose, we focus on a canonical model with iso-elastic and quasi-linear preferences and consider both rational and non-rational taxpayers. Thereby, we provide an empirically applicable recipe how to design tax reforms that raise tax revenue without making any individual in society worse off.

Mathieu PARENTI - PSE & INRAE

ygustave — 2025-10-06T11:59:22Z

"An economic analysis of extra-territorial taxation, joint with G. Zucman"

Abstract :

This paper proposes an economic analysis of extraterritorial tax policy. We consider a country imposing top-up taxes to the foreign profits of multinational firms to ensure a minimum effective corporate tax rate. We analyze the incidence of this tax, its domestic and global welfare effects, and derive conditions for optimal unilateral policy in a flexible multinational monopoly model. We obtain four main results. First, extraterritorial taxation generates additional tax revenues but leads to domestic price increases. When foreign profits are not taxed, the tax revenue gains dominate consumer welfare losses even for small countries. Second, when the foreign tax rate is positive, welfare effects are ambiguous. The optimal extraterritorial rate rises with domestic market shares and falls with foreign tax rates. A large enough country (or coalition of countries) can top-up foreign taxes, but a small country alone cannot overtax firms that are already heavily taxed abroad. Third, taxing the undertaxed profits of foreign multinationals has generally better welfare effects than tariffs. Last, revenue gains from extraterritorial profit taxation increase quadratically with country size. Extraterritorial tax collection turns the logic of tax competition on its head : large destination market countries (for which revenue gains typically swamp price increases) have incentives to tax the undertaxed profits of multinational firms, which can lead to a race-to-the-top with corporate income tax rates.