In portfolio risk minimization, the inverse covariance matrix prescribes the hedge trades in which a stock is hedged by all the other stocks in the portfolio. In practice with finite samples, however, multicollinearity makes the hedge trades too unstable and unreliable. By shrinking trade sizes and reducing the number of stocks in each hedge trade, we propose a “sparse” estimator of the inverse covariance matrix. Comparing favorably with other methods (equal weighting, shrunk covariance matrix, industry factor model, nonnegativity constraints), a portfolio formed on the proposed estimator achieves significant out-of-sample risk reduction and improves certainty equivalent returns after transaction costs.

Target acquisitiveness stands out as one of the primary drivers of all the key aspects of the market for corporate takeovers: acquisition announcement returns, probability of deal success, propensity to acquire and be acquired. Acquisitive targets, though a small proportion of the sample, are responsible for half of the overall negative acquisition announcement returns. Our large body of empirical evidence consistently supports the view that the motivation behind acquisitions of acquisitive targets is defensive: acquirers “eat in order not to be eaten”.

We examine the role of firms' government connections, defined by government intervention in CEO appointment and the status of state ownership, in determining the severity of financial constraints faced by Chinese firms. We demonstrate that government connections are associated with substantially less severe financial constraints (i.e., less reliance on internal cash flows to fund investment), and that the sensitivity of investment to internal cash flows is higher for firms that report greater obstacles to obtaining external funds. We also find that those large non-state firms with weak government connections, likely the engine for innovation in the coming years in China, are especially financially constrained, due perhaps to the formidable hold that their state rivals have on financial resources after the ‘grabbing-the-big-and-letting-go-the-small’ privatization program in China. Our empirical results suggest that government connections play an important role in explaining Chinese firms' financing conditions, and provide further evidence on the nature of the misallocation of credit by China's dominant state-owned banks.

We study the procompetitive gains from international trade in a quantitative model with endogenously variable markups. We find that trade can significantly reduce markup distortions if two conditions are satisfied: (i) there is extensive misallocation, and (ii) opening to trade exposes hitherto dominant producers to greater competitive pressure. We measure the extent to which these two conditions are satisfied in Taiwanese producer-level data. Versions of our model consistent with the Taiwanese data predict that opening up to trade strongly increases competition and reduces markup distortions by up to one-half, thus significantly reducing productivity losses due to misallocation.

We study how the presence of short sellers affects the incentives of the insiders to trade on negative information. We show it induces insiders to sell more (shares from their existing stakes) and trade faster to preempt the potential competition from short sellers. An experiment and instrumental variable analysis confirm this causal relationship. The effects are stronger for “opportunistic” (i.e., more informed) insider trades and when short sellers׳ attention is high. Return predictability of insider sales only occurs in stocks with high short-selling potential, suggesting that short sellers indirectly enhance the speed of information dissemination by accelerating trading by insiders.