What does a "good" company shares system look like?

[pickpacket]

I'm listening to this: https://www.youtube.com/watch?v=Rlp1cebFxEM (seen it before)

It occurred to me that it's likely that any type of stock market would open up for exploits like this. At least if player actions affect the value. And if player actions don't affect the value, then I don't see any point to a stock market.

Could any form of stock market be constructed that avoids this?

[odisseus]

Yes, any system can be gamed, the real life being no exception. However, these systems differ greatly in terms of the ease of exploiting them, and of consequences in case you get exposed. The current stock system in OpenTTD scores very low on both gauges, which is actually the motivation for overhauling it.