Publications in academic journals:

Ownership Dynamics with Multiple Insiders: The case of REITs
(with Robert H. Edelstein, Branko Urošević, and Nicholas Wonder)
Abstract:
We study ownership dynamics of multiple strategic risk-averse insiders facing a moral hazard problem. We show that, when insiders cannot commit, ex ante, to an ownership policy, the aggregate insider stake gradually declines toward the competitive market allocation. Both the speed of adjustment and the long-term equilibrium aggregate insider ownership level are greater for companies with a larger number of insiders, ceteris paribus. Using data from U.S. real estate investment trusts, we then test the model and find that the predictions of the model are verified empirically.
Published at Real Estate Economics (2010):
Edelstein, R. H., Sureda-Gomila, A., Urošević, B., and Wonder, N. X. (2010). Ownership dynamics with multiple insiders: The case of REITs. Real Estate Economics, 38(1):57–90. Link

Working papers:

Firms vs. Insiders as Traders of Last Resort
(with José M. Marín)
November, 2006
Abstract:
We explore the role of corporate insiders vs. firms as traders of last resort. We develop a simple model of insider trading in which insiders provide price support, as well as liquidity, in security markets. Consistent with the model predictions we find that in the US markets insiders' trading activities have a clear impact on return distributions. Furthermore, we provide empirical evidence on insiders transactions and firm transactions affecting returns in a different manner. In particular, while insiders' transactions (both purchases and sales) have a strong impact on skewness in the short run and to a lesser extent in short run volatility, company repurchases only have a clear impact on volatility, both in the short and the long run. We provide explanations for this asymmetry.
Available at SSRN: http://ssrn.com/abstract=945193


Insider trading and welfare when information has social value
Abstract:
This paper analyzes the welfare consequences of granting insider trading (IT) rights to a corporate manager as a compensation mechanism in the presence of two agency problems: the first is to induce the manager to gather information with social value, when the collection of this information is costly for her; the second is to induce the manager to implement shareholders’ optimal response to her private information. I examine the combination of two IT regimes, IT forbidden or permitted (imposing minimum holdings to the manager), with two information disclosure regimes: allowing or not the manager to keep her information private. Numerical analysis shows that depending on the characteristics of the firm, either completely forbidding IT or completely allowing it are the optimal IT regimes; a disclose-or-abstain rule is never an optimal regulation. Furthermore, a conflict of interest between society and entrepreneurs might arise, in this case, state intervention forbidding IT would maximize social welfare.