Focusing on the potential of information regulations, this article aims to contribute to ongoing efforts of policymakers to improve policy tools, in light of the increasing complexity of assessing the environmental impacts of new technologies and industrial corporations. Using the annual reports of corporations and performance data from the Ministry of Environmental Protection, the study analyzed the quality of responses to the amendments of Israel's Securities Regulations by major, publicly traded, polluting industrial corporations in Israel. The main theoretical claim of this paper is that within mandatory regulations there may be a large variability in the degree of specification of requirements. When considerable discretion is left to corporations, the result is a mixed mandatory-voluntary regulation regime. Our findings suggest that such variability impacts the implementation outcomes, as responses to environmental requirements depend on the level of discretion. Facilities increased their reported information, including the negative aspects, when specific mandatory prescriptions were stipulated. However, voluntary motivations did not result in the provision of information when corporations were allowed a high level of discretion. The authors recommend the delineation of exact stipulations of prescriptive requirements for the provision of comparative environmental information in order to obtain the environmental information deemed necessary.