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We offer an overlapping generations equilibrium model of cryptocurrency pricing and confront it to new data on bitcoin transactional benefits and costs. The model emphasizes that the fundamental value of the cryptocurrency is the stream of net transactional benefits it will provide, which depend on its future prices. The link between future and present prices implies that returns can exhibit large volatility unrelated to fundamentals. We construct an index measuring the ease with which bitcoins can be used to purchase goods and services, and we also measure costs incurred by bitcoin owners. Consistent with the model, estimated transactional net benefits explain a statistically significant fraction of bitcoin returns.

Taxing financial transactions is often advocated for Pigouvian reasons, when financial speculation is supposed to generate inefficiencies. We adopt instead a Mirrleesian approach, and study the optimal taxation of financial transactions when financial markets are efficient, but the tax system is imperfect, due to asymmetric information. In our model, financial transactions are used by entrepreneurs to hedge shocks on their skills, in line with the New Dynamic Public Finance literature. Entrepreneurs privately observe their skills, but trades in financial markets are publicly observable. The optimal mechanism maximizes a convex combination of utilitarian welfare and Rawlsian criterion, subject to feasibility and incentive constraints. Entrepreneurial projects are subject to liquidity shocks, which can be smoothed by conducting financial transactions. Better skilled entrepreneurs’ projects have larger expected profits, but also larger shocks. Trades therefore signal skills, implying it is optimal to tax financial transactions, in addition to capital income and wealth.

We offer an overlapping generations equilibrium model of cryptocurrency pricing and confront it to new data on bitcoin transactional benefits and costs. The model emphasizes that the fundamental value of the cryptocurrency is the stream of net transactional benefits it will provide, which depend on its future prices. The link between future and present prices implies that returns can exhibit large volatility unrelated to fundamentals. We construct an index measuring the ease with which bitcoins can be used to purchase goods and services, and we also measure costs incurred by bitcoin owners. Consistent with the model, estimated transactional net benefits explain a statistically significant fraction of bitcoin returns.

In order to share risk, protection buyers trade derivatives with protection sellers. Protection sellers’ actions affect the riskiness of their assets, which can create counter-party risk. Because these actions are unobservable, moral hazard limits risk sharing. To mitigate this problem, privately optimal derivative contracts involve variation mar-gins. When margins are called, protection sellers must liquidate some assets, depressing asset prices. This tightens the incentive constraints of other protection sellers and re-duces their ability to provide insurance. Despite this fire-sale externality, equilibrium is information-constrained efficient. Investors, who benefit from buying assets at fire-sale prices, optimally supply insurance against the risk of fire sales.

International audience; Nous étudions les comportements des participants d'un protocole de consensus lorsqu'ils présentent des comportements rationnels ou Byzantins. Nous nous inspirons des protocoles de blockchains tolérantes aux fautes Byzantines (comme Tendermint). Dans ces protocoles, les participants proposent des blocs et s'échangent des messages. Un bloc est accepté si une majorité de participants envoie le message correspondant à ce bloc (un vote), et les votants sont récompensés. Dans ce travail, nous étudions les conditions sous lesquelles ce protocole satisfait les deux propriétés suivantes : la terminaison (le système converge vers une décision) et la validité (toute décision est valide), quand certains participants sont rationnels et les autres Byzantins. Nous supposons que les participants Byzantins ont le comportement infligeant le plus de dégâts au système, tandis que les stratégies des participants rationnels forment un équilibre Bayésien parfait. Nous considérons les paramètres suivant : (i) le nombre de votes nécessaires, ν, pour qu'un bloc soit considéré comme accepté, et (ii) le nombre de participants Byzantins, noté f , dans le système. Nous obtenons les résultats suivants : Quand f ≥ ν, les blocs invalides sont acceptés, et donc la validité ne peut être garantie ; Quand f < ν, il existe un équilibre où la validité et la terminaison sont toutes deux satisfaites, par contre, il existe d'autres équilibres où la terminaison, et dans quelques cas la validité, ne sont pas satisfaites. Cela nous permet de conclure à l'existence de problèmes de coordination dans les protocoles étudiés.

We offer an equilibrium model of cryptocurrency pricing and confront it to new data on bitcoin transactional benefits and costs. The model emphasises that the fundamental value of the cryptocurrency is the stream of net transactional benefits it will provide, which depend on its future prices. The link between future and present prices implies that returns can exhibit large volatility, unrelated to fundamentals. We construct an index measuring the ease with which bitcoins can be used to purchase goods and services, and we also measure costs incurred by bitcoin owners. Consistent with the model, estimated transactional net benefits explain a statistically signicant fraction of bitcoin returns.

Protection buyers use derivatives to share risk with protection sellers, whose assets are only imperfectly pledgeable because of moral hazard. To mitigate moral hazard, privately optimal derivative contracts involve variation margins. When margins are called, protection sellers must liquidate some of their own assets. We analyse, in a general-equilibrium framework, whether this leads to inefficient fire sales. If investors buying in a fire sale interim can also trade ex ante with protection buyers, equilibrium is information-constrained efficient even though not all marginal rates of substitution are equalized. Otherwise, privately optimal margin calls are ineffciently high. To address this inefficiency, public policy should facilitate ex-ante contracting among all relevant counterparties.

We study the interaction between contracting and equilibrium pricing when risk- averse hedgers purchase insurance from risk-neutral investors subject to moral hazard. Moral hazard limits risk-sharing. In the individually optimal contract, margins are called (after bad news) to improve risk-sharing. But margin calls depress the price of investors' assets, affecting other investors negatively. Because of this fire-sale externality, there is too much use of margins in the market equilibrium compared to the utilitarian optimum. Moreover, equilibrium multiplicity can arise: In a pessimistic equilibrium, hedgers who fear low prices request high margins to obtain more insurance. Large margin calls trigger large price drops, confirming initial pessimistic expectations. Finally, moral hazard generates endogenous market incompleteness, raises risk premia, and induces contagion between asset classes.

Who provides liquidity in modern, electronic limit order book, markets? While agency trading can be constrained by conflicts of interest and information asymmetry between customers and traders, prop traders are likely to be less constrained and thus better positioned to carry inventory risk. Moreover, while slow traders'limit orders may be exposed to severe adverse selection, fast trading technology can improve traders'ability to monitor the market and avoid being picked off. To shed light on these points, we rely on unique data from Euronext and the AMF enabling us to observe the connectivity of traders to the market, and whether they are proprietary traders. We find that proprietary traders, be they fast or slow, provide liquidity with contrarian marketable orders, thus helping the market absorb shocks, even during crisis, and earn profits doing so. Moreover, fast traders provide liquidity by leaving limit orders in the book. Yet, only prop traders can do so without making losses. This suggests that technology is not enough to overcome adverse selection, monitoring incentives are also needed.

Blockchains are distributed ledgers, operated within peer-to-peer networks. If reliable and stable, they could offer a new, cost effective way to record transactions, but are they? We model the proof-of-work blockchain protocol as a stochastic game and analyse the equilibrium strategies of rational, strategic miners. Mining the longest chain is a Markov perfect equilibrium, without forking, in line with Nakamoto (2008). The blockchain protocol, however, is a coordination game, with multiple equilibria. There exist equilibria with forks, leading to orphaned blocks and persistent divergence between chains. We also show how forks can be generated by information delays and software upgrades. Last we identify negative externalities implying that equilibrium investment in computing capacity is excessive.

We design an experiment that closely emulates and tests the standard model of complete competitive markets, without imposing parametric restrictions on preferences. Consistent with theory, aggregated elicited supply and demand curves cross at the expected dividend when there is no aggregate risk, and at a lower price when there is aggregate risk. In contradiction with theory, individual participants frequently make choices that violate ?rst order stochastic dominance. We propose a random choice model which reconciles the above mentioned ?ndings and is also consistent with additional features of the data, such as, e.g., large mistakes being less frequent than smaller ones.

International audience; Derivatives activity, motivated by risk-sharing, can breed risk taking. Bad news about the risk of the asset underlying the derivative increases the expected liability of a protection seller and undermines her risk prevention incentives. This limits risk-sharing, and may create endogenous counterparty risk and contagion from news about the hedged risk to the balance sheet of protection sellers. Margin calls after bad news can improve protection sellers incentives and enhance the ability to share risk. Central clearing can provide insurance against counterparty risk but must be designed to preserve risk-prevention incentives.

Derivatives activity, motivated by risk-sharing, can breed risk taking. Bad news about the risk of the asset underlying the derivative increases the expected liability of a protection seller and undermines her risk prevention incentives. This limits risk-sharing, and may create endogenous counterparty risk and contagion from news about the hedged risk to the balance sheet of protection sellers. Margin calls after bad news can improve protection sellers incentives and enhance the ability to share risk. Central clearing can provide insurance against counterparty risk but must be designed to preserve risk-prevention incentives.

Derivatives activity, motivated by risk-sharing, can breed risk taking. Bad news about the risk of the asset underlying the derivative increases the expected liability of a protection seller and undermines her risk prevention incentives. This limits risk-sharing, and may create endogenous counterparty risk and contagion from news about the hedged risk to the balance sheet of protection sellers. Margin calls after bad news can improve protection sellers incentives and enhance the ability to share risk. Central clearing can provide insurance against counterparty risk but must be designed to preserve risk-prevention incentives.

We study the dynamics of an innovative industry when agents learn about its strength, i.e., the likelihood that it gets hit by negative shocks. Managers can exert risk-prevention export to mitigate the consequences of such shocks. As time goes by, if no shock occurs, condence improves. This attracts managers to the innovative sector. But, when condence becomes high, less managers exerting low risk-prevention export also enter. This accelerates the growth of the industry, while inducing a decline in risk-prevention. The longer the boom, the stronger the condence, the larger the losses if a shock occurs. While the above dynamics arise in the first best, with asymmetric information there is excessive entry of inefficient managers, earning informational rents at the expense of inneficient managers. This inflates the innovative sector and increases its vulnerability.

Information collection, processing and dissemination financial institutions is challenging. This can delay the observation by traders of the exact capital charges and constraints of their institution. During this delay, traders face preference uncertainty. In this context, we study optimal trading strategies and equilibrium prices in a continuous centralized market. We focus on liquidity shocks, during which preference uncertainty is likely to matter most. Preference uncertainty generates allocative ineficiency, but need not reduce prices. Traders progressively learning about the preferences of their institution conduct round-trip trades, which generate excess volume relative to the frictionless market. In a cross section of liquidity shocks, the initial price drop is positively correlated with total trading volume. Across traders, the number of round-trips is negatively correlated with trading profits and average inventory.

The rents agents can extract from principals increase with the magnitude of incentive problems, which the literature usually takes as given. We endogenize it, by allowing agents to choose technologies that are more or less opaque and correspondingly prone to agency problems. In our overlapping generations model, agents compete with their predecessors. We study whether the presence of old- timers earning low rents can keep young managers' rent-seeking in check. With dynamic contracts, long horizons help principals incentivize agents. Hence, old agents are imperfect substitutes for young ones. This mutes down competition between generations, especially if compensation deferral is strong. As a result, young managers can opt for more opaque and complex technologies, and therefore larger rents, than their predecessors. Thus, in equilibrium, complexity and rents rise over time.