From working at places that do electronic trading, most have some sort of central db, as well as procedures that mostly work for those times when you realize it's a trading holiday or a special session Right Now.
What's worse is when timezones/DST changes at short notice, because that involves rolling tzdb, or shudder the JVM.
I think the relevant rule is section 4.5.4 of the App Store Review Guidelines:
> 4.5.4 Push Notifications must not be required for the app to function, and should not be used to send sensitive personal or confidential information. Push Notifications should not be used for promotions or direct marketing purposes unless customers have explicitly opted in to receive them via consent language displayed in your app’s UI, and you provide a method in your app for a user to opt out from receiving such messages. Abuse of these services may result in revocation of your privileges.