@Neridyan ******
You mention 2 things
1. For a foreign broker
If you actually mean you are trading on behalf of a foreign broker then you are working for that broker, but if you are simply using a broker account to do your own personal trading you are not.
2. Financial management
If you are operating entirely on your own behalf with only your own money it's not a lot different to moving money around bank accounts to get the best interest rate. I'd suggest it probably depends on the frequency of your trades, if you are buying and selling every day it's more like work, but if the majority of days you are just monitoring your investments waiting for a buy or sell opportunity then that would not seem like work, more personal financial management