Long-term stock investment spanning multiple generations

Question

Is there any financial product that would allow someone to invest a sum X (once or maybe add funds periodically) in a single stock, an ETF or similar for a minimum period of time, say 100 years?

I'm aware that there are products like "fixed deposit", which guarantee a specific ROI on the long-term investment (usually no more than a few years?), but the question is not about a predefined ROI.

For example, if someone wanted to invest money in the stock market for their (yet to be born) great-grandchildren, is there a way to ensure the money stays invested until a substantial increase in value has happened hopefully, and to prevent intermediate generations from selling earlier?

Answer 1

I don't know about other jurisdictions or Germany, but in the UK the solution to this problem would typically be to set up a "discretionary trust", sometimes called a "bloodline trust" for this sort of application. Some more details can be found here https://unite-wills.co.uk/guides/bloodline-wills-and-trusts or https://www.aprilking.co.uk/making-a-will/bloodline-trust-will/ for example, and googling the phrase will turn up many more.

Of course it still suffers from the problem of needing to choose some trusted person(s) or institution to act as trustees and correctly implement the wishes of the trust settlor (the person who puts assets into the trust).

And that "rule against perpetuities" mentioned in Flux's comment on your question would also seem to be a potential obstacle - as this gov.uk page points out "there rules to stop trusts in England & Wales from existing for an excessive time"; however the the current "perpetuity period" (from some 2010 legislation) seems to be 125 years which would hopefully be enough for your purposes.

UK trust law has a quirky history originating with 12th-century crusaders needing to leave their assets in the hands of a trusted party before heading off on a journey from which return was uncertain, so I'm not sure what equivalents exist in other countries, if anything.