Fiscal Policy in a Currency Union at the Zero Lower Bound

This paper constructs a two‐country core–periphery New Keynesian model of a currency union to address the interaction between the objectives of regionally directed fiscal policy constrained by a single currency and the aggregate use of fiscal policy in face of the zero lower bound (ZLB) on policy interest rates. We identify an optimal path of aggregate and relative fiscal policy responses to a negative region‐specific demand shock. Our results show that (i) in a monetary union, the optimal policy response to an asymmetric reduction in demand concentrated in the periphery always entails a relative shift of fiscal expenditure toward the worse‐affected regions, (ii) though no aggregate fiscal response is required outside the ZLB, and (iii) optimal union‐wide fiscal policy is expansionary at the ZLB. Therefore, optimal policy always entails an expansion in the periphery at the ZLB, but the optimal fiscal response in the core regions can be either expansionary or contractionary depending on the parameters of the model. However, (iv) fiscal expansion in the core is warranted if the periphery cannot implement an expansion due to constraints on public spending.     

The Interaction of Monetary and Macroprudential Policies

I analyze a New Keynesian dynamic stochastic general equilibrium (DSGE) model where the financing of productive investment is affected by a moral hazard problem. I solve for jointly Ramsey‐optimal monetary and macroprudential policies. I find that when a financial friction is present in addition to the standard nominal friction, the optimal policy can replicate the first‐best allocation if the social planner can conduct both monetary and macroprudential policy. Using monetary policy alone is not enough: a policy trade‐off between stabilizing inflation and output gap emerges. When policy follows simple rules, the source of fluctuations is relevant for the choice of the appropriate policy mix.     

Optimal Monetary Policy Rules and House Prices: The Role of Financial Frictions

We probe the scope for reacting to house prices in simple and implementable monetary policy rules, using a New Keynesian model with a housing sector and financial frictions on the household side. We show that the social‐welfare‐maximizing monetary policy rule features a reaction to house price variations, when the latter are generated by housing demand or financial shocks. The sign and size of the reaction crucially depend on the degree of financial frictions in the economy. When the share of constrained agents is relatively small, the optimal reaction is negative, implying that the central bank must move the policy rate in the opposite direction with respect to house prices. However, when the economy is characterized by a sufficiently high average loan‐to‐value ratio, then it becomes optimal to counter house price increases by raising the policy rate.     

Managing Beliefs about Monetary Policy under Discretion

In models of monetary policy, discretionary policymaking is typically constrained in its ability to manage public beliefs. However, when a policymaker possesses private information, policy actions serve as signals to the public about unobserved economic conditions and belief management becomes an integral part of optimal discretion policies. This article derives the optimal time‐consistent policy for a general linear‐quadratic setting. The optimal policy is illustrated in a simple New Keynesian model, where analytical solutions can be derived as well. In this model, imperfect information about the policymaker's output target leads to lower policy losses.     

Optimal Monetary Policy in a Model with Agency Costs

This paper integrates a fully explicit model of agency costs into an otherwise standard Dynamic New Keynesian model in a particularly transparent way. A principal result is the characterization of agency costs as endogenous markup shocks in an output‐gap version of the Phillips curve. The model's utility‐based welfare criterion is derived explicitly and includes a measure of credit market tightness that we interpret as a risk premium. The paper also fully characterizes optimal monetary policy and provides conditions under which zero inflation is the optimal policy. Finally, optimal policy can be expressed as an inflation targeting criterion that (depending upon parameter values) can be either forward or backward looking.     

Optimal Continuation versus the Timeless Perspective in Monetary Policy

The timeless‐perspective approach suggests that policymakers implement in each period policy actions conforming to a rule that would have been fully optimal to adopt in the distant past. A motivating advantage is that policy henceforth would continue by recommending the same optimality conditions if reconsidered, thereby enhancing credibility. We argue that continuation can alternatively be achieved with better results, on average, in terms of policymakers' objectives, by implementing in each period the time‐invariant policy that is optimal from the viewpoint of the contemporary understanding of objectives and constraints, but while ignoring the conditions that happen to prevail at the time.     

Optimal Monetary Policy with Countercyclical Credit Spreads

We study optimal monetary policy in a New‐Keynesian Dynamic Stochastic General Equilibrium (DSGE) model with a credit channel and relationship lending in banking. We show that borrowers' bank‐specific (deep) habits give rise to countercyclical credit spreads, which, in turn, make optimal monetary policy depart substantially from price stability, under both discretion and commitment. Our analysis shows that the welfare costs of setting monetary policy under discretion (with respect to the optimal Ramsey plan) and of using simpler suboptimal policy rules are strictly increasing in the magnitude of deep habits in credit markets and market power in banking.     

Consumer Search,Incomplete Exchange Rate Pass‐Through,and Optimal Interest Rate Policy

This paper studies utility‐maximizing monetary policy in a two‐country economy with consumer search frictions. Search frictions provide a microfoundation for incomplete exchange rate pass‐through and international deviations from the law of one price (LOP). I show that optimal interest rate policy targets deviations from the LOP and acts to mitigate the effect of search frictions. In a quantitative setting, with internationally correlated technology and preference shocks, optimal policy generates positive cross‐country correlation of nominal interest rates.     

Optimal Monetary and Fiscal Policy with a Zero Bound on Nominal Interest Rates

I characterize optimal monetary and fiscal policy in a stochastic New Keynesian model when nominal interest rates may occasionally hit the zero lower bound. The benevolent policymaker controls the short‐term nominal interest rate and the level of government spending. Under discretionary policy, accounting for fiscal stabilization policy eliminates to a large extent the welfare losses associated with the presence of the zero bound. Under commitment, the gains associated with the use of the fiscal policy tool remain modest, even though fiscal stabilization policy is part of the optimal policy mix.     

Monetary Policy and Banking Structure

In this paper, I examine the differences in optimal monetary policy in various banking systems. In particular, I compare two monetary economies: one with a competitive banking system and the other with a monopolistic one. In addition, the optimality of the discount window policy is considered. It is shown that the Friedman rule is the optimal monetary policy in a monopolistic banking economy, and the zero‐inflation policy is optimal in a competitive banking economy under appropriate parameters. In addition, the combination of the Friedman rule and the discount window policy can achieve efficient allocation in both banking systems.     

Monetary Policy Response to Oil Price Shocks

How should monetary authorities react to an oil price shock? This paper shows that in a noncompetitive economy, policies that perfectly stabilize prices entail large welfare costs, hence explaining the reluctance of policymakers to enforce them. The policy trade‐off is nontrivial because oil (energy) is an input to both production and consumption. As welfare‐maximizing policies are hard to implement and communicate, I derive a simple interest rate rule that depends only on observables but mimics the optimal plan in all dimensions. The optimal rule is hard on core inflation but accommodates oil price changes.     

Optimal Fiscal and Monetary Policy in Customer Markets

We present a model in which some goods trade in “customer markets” and advertising facilitates long‐lived relationships. We estimate the model on U.S. data and find a large congestion externality in the pricing of customer market goods. This motivates the analysis of optimal policy. Under a complete set of taxes, fiscal policy eliminates the externalities with large adjustments in tax rates on customer markets goods, while labor tax volatility remains low. Constraining the instruments to the interest rate and labor tax, the optimal labor tax displays large and procyclical fluctuations, but monetary policy is little changed compared to a model with no customer markets.     

Fiscal Sustainability in a New Keynesian Model

Recent work on optimal monetary and fiscal policy in New Keynesian models suggests that it is optimal to allow steady‐state debt to follow a random walk. In this paper we consider the nature of the time inconsistency involved in such a policy and its implication for discretionary policymaking. We show that governments are tempted, given inflationary expectations, to utilize their monetary and fiscal instruments in the initial period to change the ultimate debt burden they need to service. We demonstrate that this temptation is only eliminated if following shocks, the new steady‐state debt is equal to the original (efficient) debt level even though there is no explicit debt target in the government's objective function. Analytically and in a series of numerical simulations we show which instrument is used to stabilize the debt depends crucially on the degree of nominal inertia and the size of the debt stock. We also show that the welfare consequences of introducing debt are negligible for precommitment policies, but can be significant for discretionary policy. Finally, we assess the credibility of commitment policy by considering a quasi‐commitment policy, which allows for different probabilities of reneging on past promises.     

Price Stability in Economies with Habit Persistence

This paper shows that the divine‐coincidence does not hold in a sticky price model with external habit if a time‐varying tax rate on labor income is not implemented to fully eliminate the time‐varying distortions associated with external habit and monopoly power in goods market. The required labor income tax rate is inversely related to the risk‐free real interest rate and the markup in the goods market, but it is proportional to the degree of external habit. Under this circumstance, the optimal monetary policy commands a countercyclical interest rate, having a perfect negative correlation with tax rate in the sticky price model with external habit. If a time‐invariant tax is the only fiscal instrument, then the degree of external habit entails a gap between the private marginal rate of substitution between consumption and labor and the social marginal rate of substitution, generating an endogenous trade‐off between the stabilization of welfare‐relevant output gap and inflation. Under this circumstance, price stability is not the optimal policy. The monetary policy authority should optimally try to undo the time‐varying distortions associated with external habit and monopoly power in goods market by deviating from price stability.     

Optimal monetary policy with the cost channel

In the standard new Keynesian framework, an optimizing policy maker does not face a trade-off between stabilizing the inflation rate and stabilizing the gap between actual output and output under flexible prices. An ad hoc, exogenous cost-push shock is typically added to the inflation equation to generate a meaningful policy problem. In this paper, we show that a cost-push shock arises endogenously when a cost channel for monetary policy is introduced into the new Keynesian model. A cost channel is present when firms’ marginal cost depends directly on the nominal rate of interest. Besides providing empirical evidence for a cost channel, we explore its implications for optimal monetary policy. We show that its presence alters the optimal policy problem in important ways. For example, both the output gap and inflation are allowed to fluctuate in response to productivity and demand shocks under optimal monetary policy.     

Banking Competition,Collateral Constraints,and Optimal Monetary Policy

We analyze optimal monetary policy in a model with two distinct financial frictions: monopolistically competitive banks that charge endogenous lending spreads, and collateral constraints. We show that welfare maximization is equivalent to stabilization of four goals: inflation, output gap, the “consumption gap” between borrowers and savers, and a “housing gap” that measures the distortion in the distribution of the collateralizable asset between both groups. Collateral constraints create a trade‐off between stabilization goals. Following both productivity and financial shocks, and relative to strict inflation targeting, the optimal policy implies sharper movements in the policy rate, aimed primarily at reducing fluctuations in asset prices and hence in borrowers' net worth. The policy trade‐offs become amplified as banking competition increases, due to the fall in lending spreads and the resulting increase in borrowers' leverage.     

Phillips Curve Instability and Optimal Monetary Policy

Empirical evidence suggests the Phillips curve has flattened over the past few decades. To capture this feature of the data, I develop a framework where firms face a changing cost of price adjustment, which produces a Phillips curve with a slope coefficient that varies over time. To evaluate the implications for monetary policy, I construct the utility‐based welfare criterion where the relative weight on output gap deviations changes synchronously with the slope of the Phillips curve. The systematic component of the rule that implements optimal policy is constant under discretion and commitment.     

Optimal sustainable monetary policy

In recent monetary policy literature, optimal commitment policy and its variant from a timeless perspective have been studied with emphasis on welfare gains from policy commitment. These policies, however, involve a time-consistency problem called a stabilization bias in forward-looking models. We analyze Chari and Kehoe's [1990. Sustainable plans. Journal of Political Economy 98, 783-802] sustainable equilibrium and examine optimal sustainable policy, i.e. a policymaker's strategy in the best sustainable equilibrium. This paper shows that such a policy becomes consistent with the optimal commitment policy in sufficiently later periods. It also shows that whether the optimal sustainable policy can attain the Ramsey equilibrium outcome depends on the magnitude of shocks hitting the model economy. Moreover, the paper finds a sustainable policy that attains higher social welfare than discretionary policy does.