It might be illegal and would definitely be unethical if the subscribers to the lower tier don't even know that a higher tier exists. They would be buying acce

It might be illegal and would definitely be unethical if the subscribers to the lower tier don't even know that a higher tier exists. They would be buying access on the presumption that everyone else were getting the data at the same time. If enough sufficiently large investors receive the data earlier the lower-tier subscribers won't get much benefit from their subscription at all.