We study effort and risk-taking behaviour in an economy with a continuum of principal–agent pairs where each agent exerts costly hidden effort. Principals write contracts based on both absolute and relative performance evaluations (APE and RPE, respectively) to make individually optimal risk–return trade-offs but do not take into account their impact on endogenously determined aggregate variables. This results in contractual externalities when these aggregate variables are used as benchmarks in contracts. Contractual externalities have welfare changing effects when principals put too much weight on APE or RPE due to information frictions. Relative to the second best, if the expected productivity is high, risk-averse principals over-incentivize their own agents, triggering a rat race in effort exertion, resulting in over-investment in effort and excessive exposure to industry risks. The opposite occurs when the expected productivity is low, inducing pro-cyclical investment and risk-taking behaviours.

Feedback effects from asset prices to firm cash flows have been empirically documented. This finding raises a question for asset pricing: How are asset prices determined if price affects fundamental value, which in turn affects price? In this environment, by buying assets that others are buying, investors ensure high future cash flows for the firm and subsequent high returns for themselves. Hence, investors have an incentive to coordinate, which may generate self‐fulfilling beliefs and multiple equilibria. Using insights from global games, we pin down investors' beliefs, analyze equilibrium prices, and show that strong feedback leads to higher excess volatility.

Borrowers obtain liquidity by issuing securities backed by the current period payoff and resale price of a long-lived collateral asset, and they are privately informed about the payoff distribution. Asset price can be self-fulfilling: a higher asset price lowers adverse selection and allows borrowers to raise greater funding, which makes the asset more valuable, leading to multiple equilibria. Optimal security design eliminates multiple equilibria, improves welfare, and can be implemented as a repo contract. Persistent adverse selection lowers debt funding, generates volatility in asset prices, and exacerbates credit crunches. The theory demonstrates the role of asset-backed securities on stability of market-based financial systems.

We study a model in which a capital provider learns from the price of a firm's security in deciding how much capital to provide for new investment. This feedback effect from the financial market to the investment decision gives rise to trading frenzies, in which speculators all wish to trade like others, generating large pressure on prices. Coordination among speculators is sometimes desirable for price informativeness and investment efficiency, but speculators' incentives push in the opposite direction, so that they coordinate exactly when it is undesirable. We analyze the effect of various market parameters on the likelihood of trading frenzies to arise.