> I assume DOJ can't prosecute when SEC comes to a settlement agreement?

This is incorrect. The SEC has no prosecution authority. That means it can't prosecute. It also means it can't take criminal prosecution off the table.

That's not a good assumption. Parallel enforcement routinely happens. Sometimes simultaneously, sometimes later. Sometimes both are reported in the same places, other times one is not reported at all except on DOJ's own website or in more obscure court dockets. Sometimes there is no referral. Sometimes the DOJ passes on it.