A growing literature investigates the association between stock return variation and several aspects of information and governance structures, in both a cross-country setting and a cross-firm setting within the U.S. Papers use either idiosyncratic stock return volatility or R2 as interchangeable measures of firm-specific return variation but report inconsistent results. An important reason for the differing interpretations is the assumption about whether lower R2 (or higher ) captures firm-specific news or noise. We document that higher (or equivalently, lower R2) resembles noise. In addition, we show, analytically and empirically, that different results obtain when using R2 or because the systematic risk inherent in the R2 metric is also correlated with the independent variable of interest. Therefore, we recommend that when assessing the association between R2 (or ) and some independent variable, researchers (1) control for elements of systematic risk and (2) triangulate their findings with other measures of information environment.
Data Availability: The data in this study are available from commercial providers, e.g., WRDS, Compustat, CRSP, I/B/E/S.
Fructus crataegi (hawthorn) is the common name of all plant species in the genus Crataegus of the Rosaceae family. In the present study, three monomers of (+)-catechin (C), (−)-epicatechin gallate (ECg) and (−)-epigallocatechin (EGC) were isolated from the hawthorn under the guide of antibacterial sensitization activity. The bioactivity of the composite fraction in enhancing the antibacterial effect of oxacillin against methicillin-resistant Staphylococcus aureus (MRSA) was greater than that of the individual monomer of the hawthorn extract in vitro. Two-fold dilution and checkerboard methods were used to analyze antibacterial activity and screen for the combination and proportion of monomers with the best bioactivity. The result showed that C (128 mg/L) combined with ECg (16 mg/L) had the greatest effect and the combination also reduced the bacterial load in blood of septic mice challenged with a sublethal dose of MRSA, increased daunomycin accumulation within MRSA and down-regulated the mRNA expression of norA, norC and abcA, three important efflux pumps of MRSA. In summary, C and ECg enhanced the antibacterial effect of β-lactam antibiotics against MRSA in vitro and in vivo, which might be related to the increased accumulation of antibiotics within MRSA via suppression of important efflux pumps’ gene expression.
We examine whether customer-base concentration has a differential impact on profitability for firms contracting with major government customers versus firms contracting with major corporate customers. We document that firm profitability increases with the concentration of major government customers, but decreases with the concentration of major corporate customers. We attribute the contrasting results to the differential impact of major government and corporate customers on demand uncertainty. Specifically, firms contracting with major government customers face lower demand uncertainty that enables them to realize more efficiency gains from customer-specific investments, whereas firms contracting with major corporate customers are exposed to higher demand uncertainty that reduces the efficiency of customer-specific investments. Overall, our study suggests that major government customers are unique and important in the composition of customer base, and they impact firm outcomes in a significantly different way than major corporate customers.
JEL Classifications: M41; L25; G14; H57.
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