Iron Man: Pretty sure Stark has never died. Captain America: Cap was killed when he was shot after losing out the long-drawn registration battle against Stark and the government (the conclusion to the Civil War arc in Fallen Son: The Death of Captain America). But he wasn't actually dead.
Minors (individuals under age 18) and people who are mentally incompetent do not have the legal capacity to enter into contracts. All other people are considered to have the legal capacity to enter into contracts. In New Mexico and most states, the legal age for entering into contracts is 18 (see NMSA Â§28-6-1). A contract between a minor and an adult may be cancelled upon request of the minor, but is binding on the adult.
The reason for this is, children under 18 (Sorry if the term offends, but you are still technically a child) are not able to control their own finances, as you may not enter into a contract until you are 18. I would assume that as an investor, you would need to have some kind of contract.