Knowledge that Transforms

We examine the implications of portfolio theory for the cross-sectional behavior of equity trading volume. Two-fund separation theorems suggest a natural definition for trading activity: share turnover. If two-fund separation holds, share turnover must be identical for all securities. If (K + 1)-fund separation holds, we show that turnover satisfies an approximately linear K-factor structure. These implications are examined empirically using individual weekly turnover data for NYSE and AMEX securities from 1962 to 1996. We find strong evidence against two-fund separation, and a principal-components decomposition suggests that turnover is well approximated by a two-factor linear model.

An important group of traders in the foreign exchange market is governments who often adhere to a foreign exchange rate policy of occasional interventions with otherwise floating rates. In this article we provide a theoretical model and empirical evidence that government foreign exchange interventions create significant adverse selection problems for dealers. In particular, our model shows that the adverse selection component of the foreign exchange spread is positively related to the variance of unexpected intervention and that expected intervention has no impact on the spread. After controlling for inventory and order processing costs, we find that bid-ask spreads increase with U.S. dollar and German deutsche mark foreign exchange rate intervention during the period 1976-1994. Furthermore, when the intervention is decomposed into expected and unexpected components, we find a statistically and economically significant increase in spreads with the variance of unexpected intervention, while expected intervention has no significant impact on spreads.

Venture capital financing is widely believed to be influential for new innovative companies. We provide empirical evidence that venture capital financing is related to product market strategies and outcomes of start-ups. Using a unique hand-collected database of Silicon Valley high-tech start-ups we find that innovator firms are more likely to obtain venture capital than imitator firms. Venture capital is also associated with a significant reduction in the time to bring a product to market, especially for innovators. Our results suggest significant interrelations between investor types and product market dimensions, and a role of venture capital for innovative companies.

When a risk factor is missing from an asset pricing model, the resulting mispricing is embedded within the residual covariance matrix. Exploiting this phenomenon leads to expected return estimates that are more stable and precise than estimates delivered by standard methods. Portfolio selection can also be improved. At an extreme, optimal portfolio weights are proportional to expected returns when no factors are observable. We find that such portfolios perform well in simulations and in out-of-sample comparisons.

We investigate the effect of asymmetric information on prices and liquidity by analyzing trades, quotes, spreads, and depths. Information content should increase with trade size and the information asymmetry of the trading period. Results show that price and liquidity effects are significantly associated with information content as measured by both trade size and timing relative to information events. Results are stronger for purchases than sales. Quoted prices are better measures of information effects than transaction prices, because they control for bid-ask bounce. Finally, trades that a priori contain no information have no impact on prices and liquidity, despite their large size.