Dès le déclenchement de ce « fait social total » que fut la pandémie de Covid-19, la communauté scientifique de Sciences Po s'est lancée dans des analyses collectives et interdisciplinaires pour tenter de comprendre sa signification. Sidérant, impensable, incompréhensible, un événement-monde comme la pandémie de Covid-19, au moment où il se produit, prend autant de sens différents que d'acteurs chargés de le gérer et d'en parler : responsables politiques, scientifiques, médecins, médias, réseaux sociaux… Dans cette cacophonie interprétative, les sciences sociales sont d’une grande utilité. Dès le déclenchement de ce « fait social total », la communauté scientifique de Sciences Po s’est lancée dans des analyses collectives et interdisciplinaires pour tenter de comprendre sa signification. Il n’est pas seulement nécessaire d’éclairer les aspects éruptifs et disruptifs de telles crises, mais aussi de saisir ce qu’elles révèlent de nos sociétés et ce qu’elles leur font, alors que nous devons apprendre à exister avec le coronavirus, peut-être pour longtemps.

This paper studies a model of the interest-rate channel of monetary policy in which a low policy rate lowers the cost of capital for firms thereby spurring investment, but also induces destabilizing “carry trades” against their assets. If the public sector does not have sufficient fiscal capacity to cope with the large resulting private borrowing, then carry trades and productive investment compete for scarce funds, and so the former crowd out the latter. Below an endogenous lower bound, monetary easing generates only limited investment at the cost of large and socially wasteful financial risk taking.

This paper studies a model of the interest-rate channel of monetary policy in which a low policy rate lowers the cost of capital for firms thereby spurring investment, but also induces destabilizing “carry trades” against their assets. If the public sector does not have sufficient fiscal capacity to cope with the large resulting private borrowing, then carry trades and productive investment compete for scarce funds, and so the former crowd out the latter. Below an endogenous lower bound, monetary easing generates only limited investment at the cost of large and socially wasteful financial risk taking.

This paper develops a full-fledged strategic analysis of Wallace’s “game of chicken”. A public sector facing legacy nominal liabilities is comprised of fiscal and monetary authorities that respectively set the primary surplus and the price level in a non-cooperative fashion. We find that the post 2008 feature of indefinitely postponed fiscal consolidation and rapid expansion of the Federal Reserve’s balance sheet is consistent with a strategic setting in which neither authority can commit to a policy beyond its current mandate, and the fiscal authority has more bargaining power than the monetary one at each date.

When do flexible exchange rates prevent monetary and financial conditions from spilling over across currencies? We examine a model in which international investors strategically supply capital to a small inflation‐targeting economy with flexible exchange rates. For some combination of parameters, the unique equilibrium exhibits the observed empirical feature of prolonged episodes of capital inflows and appreciation of the domestic currency, followed by reversals where capital outflows go hand‐in‐hand with currency depreciation, a rise in domestic interest rates, and inflationary pressure. Arbitrarily small shocks to global financial conditions suffice to trigger these dynamics.

Building on the idea that accounting matters for corporate governance, this paper studies the equilibrium interaction between the measurement rules that firms find privately optimal, firms’ governance, and the liquidity in the secondary market for their assets. This equilibrium approach reveals an excessive use of market-value accounting: corporate performance measures rely excessively on the information generated by other firms’ asset sales and insufficiently on the realization of a firm’s own capital gains. This dries up market liquidity and reduces the informativeness of price signals, thereby making it more costly for firms to overcome their agency problems.

Affluent households can respond to taxation with means that are not economically viable for the rest of the population, such as sophisticated tax plans and international tax arbitrage. This article studies an economy in which an inequality-averse social planner faces agents who have access to a tax-avoidance technology with subadditive costs, and who can shape the risk profile of their income as they see fit. Subadditive avoidance costs imply that optimal taxation cannot be progressive at the top. This in turn may trigger excessive risk-taking. When the avoidance technology consists in costly migration between two countries that compete fiscally, we show that an endogenous increase in inequality due to risk-taking makes progressive taxation more fragile, which vindicates in turn risk-taking and can lead to equilibria with regressive tax rates at the top, and high migrations of wealth towards the smaller country.

While the debate on cost and market-value accounting has been raging for years, economists lack a framework allowing a comparison of their relative merits. This paper considers an agency model in which the measurement of an asset can be based on public market data (marking to market) and/or on the realization of its value through costly resale to an informed buyer (taking to market). At the optimal contract, noisier market data lead to cost accounting and gains trading (selling winners/keeping losers) whereas accurate data naturally favor market-value accounting. The quality of market data and the magnitude of resale costs both depend on the volume of transactions, and therefore on accounting rules. The paper studies the mutual feedback between individually optimal accounting rules and asset market liquidity. This equilibrium approach reveals a socially excessive use of market-value accounting that dries up market liquidity and reduces the informativeness of price signals.

When does the combination of flexible exchange rates and inflation-targeting monetary policy guarantee insulation from global financial conditions? We examine a dynamic global game model of international investment flows where, for some combination of parameters, the unique equilibrium exhibits the observed empirical feature of prolonged episodes of capital inflows and appreciation of the domestic currency, followed by abrupt reversals where capital outflows go hand-in-hand with currency depreciation, a domestic bond market crash, and inflationary pressure.

This paper develops a model of active asset management in which fund managers may forgo alpha-generating strategies, preferring instead to make negative-alpha trades that enable them to temporarily manipulate investors' perceptions of their skills. We show that such trades are optimally generated by taking on hidden tail risk, and are more likely to occur when fund managers are impatient and when their trading skills are scalable, and generate a high profit per unit of risk. We propose long-term contracts that deter this behavior by dynamically adjusting the dates on which the manager is compensated in response to her cumulative performance.