Dynamic Atomic Congestion Games with Seasonal Flows


Operations Research

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Départements : Economie et Sciences de la décision, GREGHEC (CNRS)

Mots clés : Network games, dynamic flows, price of seasonality, price of anarchy, max-flow min-cut

We propose a model of discrete time dynamic congestion games with atomic players and a single source-destination pair. The latencies of edges are composed by free-flow transit times and possible queuing time due to capacity constraints. We give a precise description of the dynamics induced by the individual strategies of players and of the corresponding costs, either when the traffic is controlled by a planner, or when players act selfishly. In parallel networks, optimal and equilibrium behavior eventually coincides, but the selfish behavior of the first players has consequences that cannot be undone and are paid by all future generations. In more general topologies, our main contributions are three-fold. First, we show that equilibria are usually not unique. In particular, we prove that there exists a sequence of networks such that the price of anarchy is equal to n-1, where n is the number of vertices, and the price of stability is equal to 1.Second, we illustrate a new dynamic version of Braess's paradox: the presence of initial queues in a network may decrease the long-run costs in equilibrium. This paradox may arise even in networks for which no Braess's paradox was previously known.Third, we propose an extension to model seasonalities by assuming that departure flows fluctuate periodically over time. We introduce a measure that captures the queues induced by periodicity of inflows. This measure is the increase in costs compared to uniform departures for optimal and equilibrium flows in parallel networks

Financial Transaction Taxes, Market Composition, and Liquidity


The Journal of Finance

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Départements : Finance, GREGHEC (CNRS)

Mots clés : Financial transaction tax, institutional trading, liquidity, high-frequency trading

We use the introduction of a financial transaction tax (FTT) in France in 2012 to test competing theories on the impact of FTTs. We find no support for the idea that an FTT improves market quality by affecting the composition of trading volume. Instead, our results are in line with the idea that a lower trading volume reduces liquidity, and thereby market quality. Consistent with theories of asset pricing under transaction costs, we document a shift in security holdings from short-term to long-term institutional investors. More generally, our findings confirm that moderate aggregate effects on market quality can mask large adjustments made by individual market participants

Financing Capacity Investment Under Demand Uncertainty: An Optimal Contracting Approach


Manufacturing & Service Operations Management

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Départements : Finance, GREGHEC (CNRS)

Mots clés : Capacity, Optimal Contracts, Financial Constraints, Newsvendor Model

We study the capacity choice problem of a firm whose access to capital is hampered by financial frictions in the form of moral hazard. The firm must therefore optimize not only its capacity investment under demand uncertainty, but also its sourcing of funds. Ours is the first study of this problem to follow an optimal contracting approach, where feasible source of funds are derived endogenously from fundamentals and include standard financial claims (debt, equity, convertible debt, call and put warrants, etc.) and combinations thereof. We characterize the optimal capacity level. First, we find conditions under which a feasible financial contract exists that achieves first-best. When no such contract exists, we find that under optimal financing, the choice of capacity sometimes exceeds strictly the efficient level. This runs counter to the literature on financing capacity investment in funds and the intuition that by raising the cost of external capital and hence the unit capacity cost, financial market frictions lower the optimal capacity level. We trace the value of increasing capacity beyond the efficient level to a bonus effect and a demand differentiation effect. In contrast to most of the literature on financing capacity, our results are robust to a change of financial contract

Financing Investment: The Choice between Bonds and Bank Loans


Management Science

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Départements : Finance

Mots clés : Debt structure, Capital structure, Investment, Credit supply, Competition,

We build a model of investment and financing decisions to study the choice between bonds and bank loans in a firm's marginal financing decision and its effects on corporate investment. We show that firms with more growth options, higher bargaining power in default, operating in more competitive product markets, and facing lower credit supply are more likely to issue bonds. We also demonstrate that, by changing the cost of financing, these characteristics affect the timing of investment. We test these predictions using a sample of U.S. firms and present new evidence that supports our theory

Health Cost Risk: A Potential Solution to the Annuity Puzzle


Economic Journal

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Départements : Finance, GREGHEC (CNRS)

Mots clés : Life-cycle portfolio choice;retirement;post-retirement investment

We find that health cost risk lowers optimal annuity demand at retirement. If medical expenses can be sizeable early in retirement, full annuitisation at retirement is no longer optimal because agents do not have enough time to build a liquid wealth buffer. Furthermore, large deviations from optimal annuitisation levels lead to small utility differences. Our results suggest that health cost risk can explain a large proportion of empirically observed annuity choices. Finally, allowing additional annuitisation after retirement results in welfare gains of at most 2.5% when facing health cost risk, and negligible gains without this risk

Herding and Social Media Word-of-Mouth: Evidence from Groupon

X. LI, L. WU

MIS Quarterly

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Départements : Information Systems and Operations Management, GREGHEC (CNRS)

Mots clés : Herding, word-of-mouth, social media, interaction effect, complementarity

Modern online retailing practices provide consumers with new types of real-time information that can potentially increase demand. In particular, showing past product sales information can reduce uncertainty about product quality, inducing consumers to herd. This effect could be particularly salient for experience goods due to their inherent high uncertainty about product quality. Social media word-of-mouth (WOM) can increase product awareness as product information spreads via social media, increasing demand directly and also amplifying existing quality signals such as past sales. This study examines the mechanisms behind the strategy of facilitating herding and the strategy of integrating social media platforms to understand the potential complementarities between the two strategies. We conduct empirical analysis using data from which sells goods in a fast cycle format of “daily deals”. We find that facilitating herding and integrating social media platforms are complements in generating sales, supporting that it is beneficial to combine the two strategies on social media-driven platforms. Furthermore, we find that herding is more salient for experience goods, consistent with our hypothesized mechanisms, while the effect of social media WOM does not differ between experience goods and search goods

How Do Firm Political Connections Impact Foreign Acquisitions? The Effects of Decision Makers’ Political and Firm Embeddedness


Global Strategy Journal

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Départements : Stratégie et Politique d’Entreprise, GREGHEC (CNRS)

Mots clés : political connections, non-market strategies, foreign acquisitions, French firms, mental models

Research summary: We examine how firm political connections established through the political embeddedness of senior decision makers affect firms’ foreign acquisition strategy. We argue that such political embeddedness affects the mental models of decision makers and, in turn, influences their preferences for particular strategies. We propose that political embeddedness leads to the formation of mental models that favor foreign acquisition strategies. We further argue that the firm embeddedness of politically-embedded decision makers alters their mental models, thereby mitigating their inclination for such strategies. We find evidence consistent with our mental models explanation using a sample of foreign acquisitions made by French publicly-traded firms during the 2009-2014 period. Overall, this study contributes to a better understanding of the mechanisms through which political connections impact global strategy. Managerial summary: We investigate how firm political connections affect firms’ foreign acquisition strategies. We argue that when firms have top decision makers with close connections to the government, they will make more foreign acquisitions. We further argue that this inclination towards foreign acquisitions is primarily driven by non-executive board members, with politically-connected executives appearing to be more reluctant to engage in such strategies. We find evidence consistent with these ideas when examining foreign acquisitions made by French publicly-traded firms managed by graduates of the prestigious ENA government school, which trains many government and senior civil servants in France

How Much Do Means Tested Benefits Reduce the Demand for Annuities?


Journal of Pension Economics and Finance

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Départements : Finance, GREGHEC (CNRS)

Mots clés : Means-Tested Benefits, Occupational Pension, Annuity

We analyze the effect of means-tested benefits on annuitization decisions using an administrative dataset of pension wealth cash-out choices. Availability of means-tested payments creates an incentive to cash out pension wealth for low and middle income earners, instead of taking the annuity. Agents trade off the advantages from annuitization, receiving longevity risk insurance, to the disadvantages, giving up “free” wealth in the form of means-tested supplemental income. Our life-cycle model demonstrates that the availability of means-tested benefits substantially reduces the desire to annuitize especially for low and intermediate levels of pension wealth. In our empirical analysis we show that the model’s predicted fraction of retirees choosing the annuity is able to match the annuitization pattern of occupational pension wealth observed in Switzerland

Impact of Average Rating on Social Media Endorsement: The Moderating Role of Rating Dispersion and Discount Threshold


Information Systems Research

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Départements : Information Systems and Operations Management, GREGHEC (CNRS)

Incentive programs for reducing readmissions when patient care is co-produced


Production and Operations Management

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Départements : GREGHEC (CNRS)

Mots clés : co-productive services, hospital readmissions, pay-for-performance, bundled payment

To reduce preventable readmissions, many healthcare systems are transitioning from Fee-for-Service (FFS) to other reimbursement schemes such as Pay-for-Performance (P4P) or Bundled Payment (BP) so that the funder of a healthcare system can transfer to the hospital some of the financial risks associated with patient re-hospitalizations. To examine the effectiveness of different schemes (FFS, P4P, and BP), we develop a "health co-production" model in which the patient's readmissions can be "jointly controlled" by the efforts exerted by both the hospital and the patient. Our analysis of the equilibrium outcomes reveals that FFS cannot entice the hospital and the patient to exert readmission-reduction efforts. Relative to BP, we find that P4P is more "robust" in the sense that it can induce readmission-reduction efforts under milder conditions. However, BP can induce greater efforts compared to P4P. More importantly, we characterize the conditions under which BP (or P4P) is the dominant scheme from the funder's perspective. Finally, we find that patient cost-sharing can generate two benefits: (a) it provides incentive for patients to exert efforts; and (b) if not excessive, it can reduce the readmission rate