Does owning a foreign business or partnership interest trigger FATCA reporting?

It can. Form 8938 under FATCA covers specified foreign financial assets, which include an interest in a foreign entity such as stock in a foreign corporation or a capital or profits interest in a foreign partnership, when held for investment and not inside a foreign financial account. Note that a direct interest in an active foreign business you personally run may also trigger separate, more complex filings like Form 5471 for foreign corporations or Form 8865 for foreign partnerships, which carry steep penalties for non-filing. These are among the most complicated cross-border returns. If you own more than a small stake in a foreign company, consult a cross-border CPA rather than relying on tax software, because the entity-reporting rules go well beyond Form 8938 and are easy to miss.