As a 16 year old am I able to hold shares or invest money into company of my choosing?

[Ursugardaddy]

Get yourself a ROTH IRA and do not touch this account. There is no age minimum for opening a Roth. The requirement (as far as kids are concerned) is that contributions to a Roth IRA must be from eligible earned income, and contributions cannot exceed annual income. However, some brokerages, like Fidelity as an example, may require your child to be 18 years old. In that case, you need to find a broker who will allow them to open an account
With a Roth, the younger the better because Roth gains accumulate tax free, you can withdrawal the contribution at anytime but you can not withdrawal the interest that the account have earned. That 1,500 invested would grow to $160,079.09 over the course of 49yrs. 5000 would get you around $533,595.54. By doing this, you have completed most of your retirement savings before you even started your own life at the age of 18yrs old

Hope this information helped. Take Care