I’d say it depends on if you need the data to stick forever, or if some of it could potentially change in the future. Take my situation. I use a form to submit lessons for students. I only submit the RowID of the student instead of the name because it’s possible the a spelling error could lead to the name being changed at a later date after the lesson was submitted. RowId will never change, but the name could and that would break any relations in the future. In that case I use the ID to relate to the student sheet and get the name instead of directly storing the name.
On the other hand, there is a charge rate for the lesson. I only want to save the current rate amount and not use a relation to get the rate since it is possible for the rates to change in the future and I don’t want the use of a relation to mess up any past lessons. Past lessons have already been invoiced and billed and if I used a relation to get the billing rate that has changed, all past bills would be wrong when they should never change.
In your case, I would use the ticker symbol and do a relation for the name. It’s very reasonable that a company may alter their name or logo, but the ticker symbol would never change.
Maybe an easy rule: If you are using and have access to any sort of key or ID field for what you are submitting, use it with a relation. If a key or ID isn’t related to the value, or it needs to stay permanent, then save the actual value.