We propose a theory of financial intermediaries operating in markets influenced by investor sentiment. In our model, banks make, securitize, distribute, and trade loans, or they hold cash. They also borrow money, using their security holdings as collateral. Banks maximize profits, and there are no conflicts of interest between bank shareholders and creditors. The theory predicts that bank credit and real investment will be volatile when market prices of loans are volatile, but it also points to the instability of banks, especially leveraged banks, participating in markets. Profit-maximizing behavior by banks creates systemic risk.

We present a model of mergers and acquisitions based on stock market misvaluations of the combining firms. The key ingredients of the model are the relative valuations of the merging firms and the market's perception of the synergies from the combination. The model explains who acquires whom, the choice of the medium of payment, the valuation consequences of mergers, and merger waves. The model is consistent with available empirical findings about characteristics and returns of merging firms, and yields new predictions as well.

We present a standard model of financial innovation, in which intermediaries engineer securities with cash flows that investors seek, but modify two assumptions. First, investors (and possibly intermediaries) neglect certain unlikely risks. Second, investors demand securities with safe cash flows. Financial intermediaries cater to these preferences and beliefs by engineering securities perceived to be safe but exposed to neglected risks. Because the risks are neglected, security issuance is excessive. As investors eventually recognize these risks, they fly back to the safety of traditional securities and markets become fragile, even without leverage, precisely because the volume of new claims is excessive.

We introduce the model of asset management developed in Gennaioli, Shleifer, and Vishny (“Money Doctors,” Journal of Finance , forthcoming 2015) into a Solow-style neoclassical growth model with diminishing returns to capital. Savers rely on trusted intermediaries to manage their wealth (claims on capital stock), who can charge fees above costs to trusting investors. In this model, the ratio of financial income to GDP increases with the ratio of aggregate wealth to GDP. Both rise along the convergence path to steady state growth. We examine several further implications of the model for management fees, unit costs of finance, and the consequences of shocks to trust and to the capital stock.

Several Eastern European countries have initiated mass privatization programs to transfer state-owned assets to the general population. We show that the decision to pursue mass privatization and even the specific design of the programs are largely dictated by politics. Nonetheless, politically feasible programs can also be made attractive from an economic standpoint in terms of maximizing value, fostering free and efficient markets, and promoting corporate governance. In general, the design of economic institutions is critically shaped by political factors, although satisfactory economic results can be achieved in spite of political constraints.

This paper uses new data on the holdings of 769 tax-exempt (predominantly pension) funds, to evaluate the potential effect of their trading on stock prices. We address two aspects of trading by these money managers: herding, which refers to buying (selling) simultaneously the same stocks as other managers buy (sell), and positive-feedback trading, which refers to buying past winners and selling past losers. These two aspects of trading are commonly a part of the argument that institutions destabilize stock prices. The evidence suggests that pension managers do not strongly pursue these potentially destabilizing practices.

We investigate the relationship between management ownership and market valuation of the firm, as measured by Tobin's Q. In a 1980 cross-section of 371 Fortune 500 firms, we find evidence of a significant nonmonotonic relationship. Tobin's Q first increases, then declines, and finally rises slightly as ownership by the board of directors rises. For older firms, there is evidence that Q is lower when the firm is run by a member of the founding family than when it is run by an officer unrelated to the founder.

In a January 2009 lecture on the financial crisis, Federal Reserve Chairman Bernanke advocated a new Fed policy of credit easing, defined as a combination of lending to financial institutions, providing liquidity directly to key credit markets, and buying of long term securities. We show that Bernanke's analysis and recommendations can be naturally considered in a model of "unstable banking," which relies on two mechanisms: 1) fire sales reduce asset prices below fundamental values, and 2) financial institutions prefer speculation to new lending when markets are dislocated. We analyze credit easing and compare it to alternative government interventions during the crisis.

Textbook arbitrage in financial markets requires no capital and entails no risk. In reality, almost all arbitrage requires capital, and is typically risky. Moreover, professional arbitrage is conducted by a relatively small number of highly specialized investors using other people's capital. Such professional arbitrage has a number of interesting implications for security pricing, including the possibility that arbitrage becomes ineffective in extreme circumstances, when prices diverge far from fundamental values. The model also suggests where anomalies in financial markets are likely to appear, and why arbitrage fails to eliminate them.

This article surveys research on corporate governance, with special attention to the importance of legal protection of investors and of ownership concentration in corporate governance systems around the world.