my greatest fear is to be stuck in the boring sector.
A) How many years can one cover a sector before being typecasted?
B) Would the sector I like affect your answer? I ask that because there are some sectors that are easier to understand and some that require more specific knowledge.
For instance going from Utilities to Packaged Foods might be easier than Utilities to Med Tech
If you want to shift, study up on that sector in your spare time, or try to help someone who covers that sector or who is willing to be a mentor to you. But do that only once you are up and running in your own sector.
On the buy side there’s a little more freedom to shift around companies and sectors and be a generalist, because your job is to find and go where the opportunities are, whereas on the sell side, your job is to be the go-to expert on company/industry X. Obviously, it helps to have expertise in whatever you are covering at the time, but if you want to develop expertise elsewhere, you have some lattitude to do it.