@Alex3 , please first whether the person is a visa holder ( and what kind, when did the person enter the USA etc. ) or GreenCard or citizen of USA; which country is the foreign entity ( whose shares are owned by this individual) registered in; what kind of business and of course are the shares publicly traded? Was tyhere any income distributed to the person owning the shares.
While you answer these questions, generally just because one owns shares in a foreign or domestic entity, it may or may not need to reported. All incomes are generally need to be recognized. Some foreign investmemnts may come under Mark-to-Market (MTM ) rules. There may also be requirements under FBAR and FATCA regulations. So we need to lot a lot more before we provide a specific reply
pk