In a minor's conservatory account, it is common for courts to allow
conservators to purchase low yield investments such as municipal
bonds, treasury bills, money market accounts, CD's and other low
This may have been the norm at some point but it is increasingly uncommon, although Georgia is regressive in this respect. See Georgia Code § 29-3-32. But court's can authorize less timid investments. See, e.g., Georgia Code § 29-2-33. Most courts don't specifically regulate precisely what a conservator can invest in. Instead, the conservative has a fiduciary duty to invest prudently. In Georgia law, the general obligation is found at Georgia Code § 29-3-21. The roadmap to the conservator's investment powers is found at Georgia Code §§ 29-3-22 and 29-3-34.
In practice, the modern trend is to allow conservators discretion to make prudent investments after first running an initial investment plan past the court under Georgia Code § 29-3-34. A court is generally going to accept an initial investment plan from any conservator whose appointment it previously approved, who comes up with a reasonably credible plan. The initial investment plan would accompany a motion seeking its approval filed with the court, that no one is going to contest after notice is given and a time to respond lapses. Often the motion to approve the initial plan would be supported by some sort of written statement from a financial industry professional such as a certified financial planner, or a registered investment advisor, or a broker-dealer in securities, who could provide testimony if the plan is contested.
Unless the plan is really outlandish and proposes something like penny stocks, or junk bonds, or an "all in one basket" investment portfolio, a judge is likely to approve an unopposed investment plan as a matter of course.
This means that the fiduciary needs to have a risk-reward profile appropriate for the needs of the beneficiary (e.g. does the beneficiary need some minimum amount of income flow or adult principal balance) and the beneficiary's time horizon. You invest differently for a 2 year old taken up as family by his aunt and uncle, or with funds provided by a grandparent to supplement the funds of one or both living parents, than you do for a 16 year old who will be living in an expensive boarding school and then going to an expensive private college.
It also generally means that when particular investments are individually risky, that the fiduciary has a duty to diversify the portfolio of investments.
Investments of mutual funds are common place where there aren't tight demands on cash flow or principal balances upon termination, and the time horizon is lengthy. Support trusts are typically funded with corporate bonds or annuities or mortgage backed securities or mortgages or preferred stock (or mutual fund or ETF equivalents of these), typically targeting an income stream of 4-5% per year of principal to the extent the market can produce that with only modest penetration of principal over the term of the investment.