Modern investors face a high-dimensional prediction problem: thousands of observable variables are potentially relevant for forecasting. We reassess the conventional wisdom on market efficiency in light of this fact. In our equilibrium model, N assets have cash flows that are linear in J characteristics, with unknown coefficients. Risk-neutral Bayesian investors learn these coefficients and determine market prices. If J and N are comparable in size, returns are cross-sectionally predictable ex post. In-sample tests of market efficiency reject the no-predictability null with high probability, even though investors use information optimally in real time. In contrast, out-of-sample tests retain their economic meaning.

We develop a theory of how corporate lending and financial intermediation change based on the fundamentals of the firm and its environment. We focus on the interaction between the prospective net worth or liquidity of an industry and the firm’s internal governance or pledgeability. Variations in prospective liquidity can induce changes in the nature, covenants, and quantity of loans that are made, the identity of the lender, and the extent to which the lender is leveraged. We offer predictions on how these might vary over the financial cycle.

Using novel credit data, we show that hedge fund borrowing is significantly overcollateralized, primarily with rehypothecable securities. An idiosyncratic liquidity shock to a major prime broker significantly decreases credit to connected hedge funds. The dominant channel behind this shock transmission is credit supply reduction rather than precautionary demand reduction. Funds posting more rehypothecable collateral are less affected because their collateral alleviates prime broker liquidity constraints. Exposed funds subsequently have lower aggregate credit with worse terms, suggesting imperfect substitutability across hedge fund credit sources. Funds subject to the decrease in balance sheet leverage subsequently increase portfolio illiquidity, embedded leverage, and derivatives exposure.

Using unique data, this paper examines investment banks’ choice of peers in comparable companies analysis in mergers and acquisitions. We find strong evidence that product market space is amongst the most important factors in peer selection, but Standard Industrial Classification (SIC) codes, particularly three and four digit codes, do a poor job of categorizing related firms in this setting. Banks strategically select large, high growth peers with high valuation multiples, factors that are also positively related to premiums. Our evidence is consistent with target-firm advisors selecting peers with high valuation multiples to negotiate higher takeover prices.

We use the COVID shock to study the direct and interactive effects of several forms of corporate flexibility on short- and long-term real business plans. We find that i) workplace flexibility, namely the ability for employees to work remotely, plays a central role in determining firms’ employment plans during the health crisis; ii) investment flexibility allows firms to increase or decrease capital spending based on their business prospects in the crisis, with effects shaped by workplace flexibility; and iii) financial flexibility contributes to stronger employment and investment, in particular when fixed costs are high. While the role of workplace flexibility is new to the COVID crisis, CFOs expect lasting effects for years to come: high workplace flexibility firms foresee continuation of remote work, stronger employment recovery, and shifting away from traditional capital investment, whereas low workplace flexibility firms rely more on automation to replace labor.

We study brokerage platform outages to examine the impact of retail investors on financial markets. We contrast outages at Robinhood, which caters to inexperienced investors, with outages at traditional retail brokers. For stocks with high retail interest, we find that negative shocks to Robinhood investor participation are associated with reduced market order imbalances, increased market liquidity, and lower return volatility, whereas the opposite relations hold following outages at traditional retail brokerages. The findings suggest that herding by inexperienced investors can create inventory risks that harm liquidity in stocks with high retail interest, while other retail trading improves market quality.