Answer:
not sufficiently profitable to cover trading costs.
Step-by-step explanation:
Hasan Nejat Seyhun, a professor of Finance, in 1986, in his research study titled "Insiders' profits, costs of trading, and market efficiency" investigates the unusual findings of the previous insider trading studies, that suggests that, any investor can earn abnormal profits by reading the Official Summary.
Hence, he concluded that, that the practice of monitoring insider trade disclosures, and trading on that information, would be not sufficiently profitable to cover trading costs.