What year of age is required to open a brokerage account and start trading? Is it 18+ or 21+? I live in Israel, but am interested in trading in the U.S. markets.
In the U.S., handful of states allow a citizen to open a brokerage account at age 18. In most states the age is 21. A parent or legal guardian can open a Custodial Account for a child who wants to invest but the adult administers the account (places the orders).
U.S. citizenship is not required to trade U.S. securities but brokers can put conditions on your market access. There are international brokers which permit trading in as well as from many countries.
Two brokers considered very good for foreign investment by U.S citizens are Interactive Brokers and Fidelity. I would assume that the converse should be true, namely that they would also be good for residents of foreign countries who wish to invest in the U.S.