The foreign "mystery company" fighting the subpoena is a financial institution,

according to two WA Post sources.

https://www.washingtonpost.com/politics/courts_law/supreme-court-rules-against-mystery-corporation-from-country-a-fighting-subpoena-in-mueller-investigation/2019/01/08/a39b61ac-0d1a-11e9-84fc-d58c33d6c8c7_story.html?utm_term=.1ab38418edc5

The Supreme Court on Tuesday left in place a lower-court order requiring an unnamed foreign-owned corporation to comply with a subpoena said to be part of special counsel Robert S. Mueller III’s investigation of Russian interference in the 2016 election.

The court dissolved a temporary stay that had been put in place by Chief Justice John G. Roberts Jr. In a short order, it did not give a reason for the decision nor note any dissents.

The entity that is the subject of the cloaked legal battle — known in court papers simply as a “Corporation” from “Country A” — is a foreign financial institution that was issued a subpoena by a grand jury hearing evidence in the special counsel investigation, according to two people familiar with the case.

SNIP

Earlier Tuesday, the corporation’s lawyers indicated that they plan to continue fighting the subpoena, asking the Supreme Court to review the merits of the decision by U.S. Court of Appeals for the D.C. Circuit.

SNIP