31 U.S. Code § 5312 – Definitions and application:
(2)“financial institution” means—
(A)an insured bank (as defined in section 3(h) of the Federal Deposit Insurance Act (12 U.S.C. 1813(h)));
(B)a commercial bank or trust company;
(C)a private banker;
(D)an agency or branch of a foreign bank in the United States;
(E)any credit union;
(F)a thrift institution;
(G)a broker or dealer registered with the Securities and Exchange Commission under the Securities Exchange Act of 1934 (15 U.S.C. 78a et seq.);
(H)a broker or dealer in securities or commodities;
(I)an investment banker or investment company;
(J)a currency exchange, or a business engaged in the exchange of currency, funds, or value that substitutes for currency or funds;
(K)an issuer, redeemer, or cashier of travelers’ checks, checks, money orders, or similar instruments;
(L)an operator of a credit card system;
(M)an insurance company;
(N)a dealer in precious metals, stones, or jewels;
(O)a pawnbroker;
(P)a loan or finance company;
(Q)a travel agency;
(R)a licensed sender of money or any other person who engages as a business in the transmission of currency, funds, or value that substitutes for currency, including any person who engages as a business in an informal money transfer system or any network of people who engage as a business in facilitating the transfer of money domestically or internationally outside of the conventional financial institutions system;
(S)a telegraph company;
(T)a business engaged in vehicle sales, including automobile, airplane, and boat sales;
(U)persons involved in real estate closings and settlements;
(V)the United States Postal Service;
(W)an agency of the United States Government or of a State or local government carrying out a duty or power of a business described in this paragraph;
(X)a casino, gambling casino, or gaming establishment with an annual gaming revenue of more than $1,000,000 which—
(i)is licensed as a casino, gambling casino, or gaming establishment under the laws of any State or any political subdivision of any State; or
(ii)is an Indian gaming operation conducted under or pursuant to the Indian Gaming Regulatory Act other than an operation which is limited to class I gaming (as defined in section 4(6) of such Act);
(Y)any business or agency which engages in any activity which the Secretary of the Treasury determines, by regulation, to be an activity which is similar to, related to, or a substitute for any activity in which any business described in this paragraph is authorized to engage; or
(Z)any other business designated by the Secretary whose cash transactions have a high degree of usefulness in criminal, tax, or regulatory matters.