1. If Coinbase itself had purchased a bunch of coins before listing on its own exchange, would that be illegal?
2. If the employee had purchased coins that were correlated with the ones that were listed, but not the specific ones that were listed, would that be illegal?
With 1. I think it depends on intent. For example when Tesla purchased BTC before announcing they were taking payments to have some liquidity on it for financial reasons or whatever, then it's ok. If you can prove they are front-running the market because for example right after announcing they are listing a coin they dump what they got before listing it then yeah maybe that's insider trading.
The thing is if they take enough measures to prevent their employees from doing it. It's hard considering they can do it on another exchange, but at least on their own exchange my understanding is they should prevent their employees from trading if they have privileged information.
1. Unlikely, it's just investing. You are expected to gain from your investment, to promote it, etc. Like how companies buy and sell their own stock all the time and it's not considered insider trading.
2. Yes, since the fact that the coin was to be listed was inside information. You will be accused of insider trading if you trade correlated assets. Obviously there is a threshold somewhere, like if you have positive insider info on TSLA and you invest in a passive stock market index fund.
1. If Coinbase itself had purchased a bunch of coins before listing on its own exchange, would that be illegal?
2. If the employee had purchased coins that were correlated with the ones that were listed, but not the specific ones that were listed, would that be illegal?