I consider three views of the labor market. In the first, wages are flexible and employment follows the principle of bilateral efficiency. Workers never lose their jobs because of sticky wages. In the second, wages are sticky and inefficient layoffs do occur. In the third, wages are also sticky, but employment governance is efficient. I show that the behavior of flows in the labor market strongly favors the third view. In the modern U.S. economy, recessions do not begin with a burst of layoffs. Unemployment rises because jobs are hard to find, not because an unusual number of people are thrown into unemployment.

Excessive layoffs in bad times and excessive quits in good times both stem from the same weakness in practical employment arrangements: the specific nature of worker-firm relations creates a situation of bilateral monopoly. Institutions which have arisen to avert the associated inefficiency cannot mimic the separation decisions of a perfect-information, first-best allocation rule. Simple employment rules based on predetermined or indexed wages are in many cases the most desirable among the class of feasible employment arrangements. More complicated contracts which seem to deal more effectively with turn-over issues either are infeasible because of informational requirements or create adverse incentives on some other dimension.

Unemployment is high when financial discounts are high. In recessions, the stock market falls and all types of investment fall, including employers' investment in job creation. The discount rate implicit in the stock market rises, and discounts for other claims on business income also rise. A higher discount implies a lower present value of the benefit of a new hire to an employer. According to the leading view of unemployment—the Diamond-Mortensen-Pissarides model—when the incentive for job creation falls, the labor market slackens and unemployment rises. Thus high discount rates imply high unemployment.

In a market-clearing economy, declines in demand from one sector do not cause large declines in aggregate output because other sectors expand. The key price mediating the response is the interest rate. A decline in the rate stimulates all categories of spending. But in a low-inflation economy, the room for a decline in the rate is small, because of the notorious lower limit of zero on the nominal interest rate. In the Great Depression, substantial deflation caused the real interest rate to reach high levels. In the Great Slump that began at the end of 2007, low inflation resulted in an only slightly negative real rate when full employment called for a much lower real rate because of declines in demand. Fortunately, the inflation rate hardly responded to conditions in product and labor markets, else deflation might have occurred, with an even higher real interest rate. I concentrate on three closely related sources of declines in demand: the buildup of excess stocks of housing and consumer durables, the corresponding expansion of consumer debt that financed the buildup, and financial frictions that resulted from the decline in real-estate prices.

Following a recession, the aggregate labor market is slack–employment remains below normal and recruiting efforts of employers, as measured by help-wanted advertising and vacancies, are low. A model of matching friction explains the qualitative responses of the labor market to adverse shocks, but requires implausibly large shocks to account for the magnitude of observed fluctuations. The incorporation of wage stickiness vastly increases the sensitivity of the model to driving forces. I develop a new model of the way that wage stickiness affects unemployment. The stickiness arises in an economic equilibrium and satisfies the condition that no worker-employer pair has an unexploited opportunity for mutual improvement. Sticky wages neither interfere with the efficient formation of employment matches nor cause inefficient job loss. Thus the model provides an answer to the fundamental criticism previously directed at sticky-wage models of fluctuations.

Strong and widely accepted evidence shows that the natural rate of unemployment varies over time with substantial amplitude. The frictions in the labor market that account for positive normal levels of unemployment are not simple and mechanical. Instead, as a rich modern body of theory demonstrates, the natural rate of unemployment is an equilibrium in which the volumes of job-seeking by workers and worker-seeking by employers reach a balance controlled by fundamental determinants of the relative prices of the two activities. In recessions, unemployment rises, and job vacancies fall. The natural explanation is an economywide fall in labor demand. But a compelling model that generates a fall in labor demand without a counterfactual fall in productivity has eluded theorists to date. Nonetheless, policymakers have appropriately adopted the view that the natural rate varies over time and is not a simple benchmark for setting monetary instruments.

Economists are as perplexed as anyone by the behavior of the stock market. Figure 1 shows a broad measure of stock-market value in relation to GDP from 1947 through 2000. In addition to saw-tooth movements including the contraction in late 2000, the value of the stock market has large, low-frequency swings, moving upward from 1950 to 1965, then downward to 1982, and upward until early 2000. I entertain the hypothesis that these large movements are the result of rational (if not accurate) appraisal of the cash likely to be received by shareholders in the future. The hypothesis receives some support from work by financial economists showing that irrational markets create profit opportunities for active traders and that passive traders consistently earn higher returns. Most of my discussion will be complementary to the work of financial economists—I will look at the fundamentals underlying stock-market values. The lecture considers three potential contributors to the big movements shown in Figure 1:

The value of a firm's securities measures the value of the firm's productive assets. If the assets include only capital goods and not a permanent monopoly franchise, the value of the securities measures the value of the capital. Finally, if the price of the capital can be measured or inferred, the quantity of capital is the value divided by the price. A standard model of adjustment costs enables the inference of the price of installed capital. Data from U.S. corporations over the past 50 years imply that corporations have formed large amounts of intangible capital, especially in the past decade.