To steal or not to steal: Firm attributes, legal environment, and valuation

Newly released data on corporate governance and disclosure practices reveal wide within-country variation, with the variation increasing as legal environment gets less investor friendly. This paper examines why firms practice high-quality governance when law does not require it; firm attributes that are related to the quality of governance; how the attributes interact with legal environment; and the relation between firm valuation and corporate governance. A simple model, in which a controlling shareholder trades off private benefits of diversion against costs that vary across countries and time, identifies three relevant firm attributes: investment opportunities, external financing, and ownership structure. Using firm-level governance and transparency data on 859 firms in 27 countries, we find that firms with greater growth opportunities, greater needs for external financing, and more concentrated cash flow rights practice higher-quality governance and disclose more. Moreover, firms that score higher in governance and transparency rankings are valued higher in the stock market. Equally important, all these relations are stronger in countries that are less investor friendly, demonstrating that firms do adapt to poor legal environments to establish efficient governance practices.http://deepblue.lib.umich.edu/bitstream/2027.42/39939/3/wp554.pd

The Unanticipated Effects of Insider Trading Regulation

Using a sample of 2,827 firms from 21 countries we examine whether insider trading laws achieve the primary objective for which they are introduced – protecting uninformed investors from private information-based trading. We find that when control is concentrated in the hands of a large shareholder, insider trading regulation is less effective in reducing private information-based trading if investor protection is poor. We suggest that controlling shareholders who are banned from trading may resort to covert expropriation of firm resources, creating more information asymmetry and thereby encouraging private information trading by informed outsiders. Consistent with this, we find evidence that when the rights of controlling shareholders are high, insider trading restrictions are associated with greater earnings opacity.http://deepblue.lib.umich.edu/bitstream/2027.42/40081/3/wp695.pd

High-frequency nonlinear transport and photogalvanic effects in two-dimensional topological insulators

Excitation of a topological insulator by a high-frequency electric field of a laser radiation leads to a dc electric current in the helical edge channel whose direction and magnitude are sensitive to the radiation polarization and depend on the physical properties of the edge. We present an overview of theoretical and experimental studies of such edge photoelectric effects in two-dimensional topological insulators based on semiconductor quantum wells. First, we give a phenomenological description of edge photocurrents, which may originate from the photogalvanic effects or the photon drag effects, for edges of all possible symmetry. Then, we discuss microscopic mechanisms of photocurrent generation for different types of optical transitions involving helical edge states. They include direct and indirect optical transitions within the edge channel and edge-to-bulk optical transitions.Comment: 13 pages, 8 figures, 2 table

The Unanticipated Effects of Insider Trading Regulation

Using a sample of 2,827 firms from 21 countries we examine whether insider trading laws achieve the primary objective for which they are introduced – protecting uninformed investors from private information-based trading. We find that when control is concentrated in the hands of a large shareholder, insider trading regulation is less effective in reducing private information-based trading if investor protection is poor. We suggest that controlling shareholders who are banned from trading may resort to covert expropriation of firm resources, creating more information asymmetry and thereby encouraging private information trading by informed outsiders. Consistent with this, we find evidence that when the rights of controlling shareholders are high, insider trading restrictions are associated with greater earnings opacity.Insider Trading Regulation, Ownership, Private Information Trading, Earnings Opacity

Phase diagrams of magnetopolariton gases

The magnetic field effect on phase transitions in electrically neutral bosonic systems is much less studied than those in fermionic systems, such as superconducting or ferromagnetic phase transitions. Nevertheless, composite bosons are strongly sensitive to magnetic fields: both their internal structure and motion as whole particles may be affected. A joint effort of ten laboratories has been focused on studies of polariton lasers, where non-equilibrium Bose-Einstein condensates of bosonic quasiparticles, exciton-polaritons, may appear or disappear under an effect of applied magnetic fields. Polariton lasers based on pillar or planar microcavities were excited both optically and electrically. In all cases a pronounced dependence of the onset to lasing on the magnetic field has been observed. For the sake of comparison, photon lasing (lasing by an electron-hole plasma) in the presence of a magnetic field has been studied on the same samples as polariton lasing. The threshold to photon lasing is essentially governed by the excitonic Mott transition which appears to be sensitive to magnetic fields too. All the observed experimental features are qualitatively described within a uniform model based on coupled diffusion equations for electrons, holes and excitons and the Gross-Pitaevskii equation for exciton-polariton condensates. Our research sheds more light on the physics of non-equilibrium Bose-Einstein condensates and the results manifest high potentiality of polariton lasers for spin-based quantum logic applications.Comment: 21 pages, 11 figure