Establishing shadow trading criteria
Because this case is still pending, it's impossible to know what the future criteria may be for shadow trading, but it seems to hinge on three specific items in the SEC's current case.
First, the information being used in trading had to be material, confidential, and nonpublic. It was, and Panuwat had signed various agreements regarding its use.
Second, the purchase had to represent a breach of his fiduciary duties. Because Panuwat agreed to the company's insider trading policy, he also allegedly violated it. The specific verbiage includes prohibitions on investing in other publicly traded companies, including the competition.
Third, the purchase had to be made based on the MNPI. Panuwat made his investment very soon after learning about the acquisition of his own company, which would further shrink the pool of similar investable companies. He had never traded the competitor company before the MNPI.