MSF 3+1

I am not sure if I understand your situation perfectly but I can chime in and possibly help.

At my undergrad, you are able to get your MSF after you complete your BS/BA degree. You would just continue to be enrolled in your school as if you were a continuing student.

Some people at my school missed IB SA recruiting so they decided to push back a semester to re-recruit. They exploited the above to re-recruit. They would add on an MSF to their BS/BA degree so they would graduate in 4.5 - 5 years, depending on how many credits they had. Logistically, this meant they graduated with their BS/BA in May, interned as a SA from June - August, and then returned to school after SA to finish their MSF. If they finished the MSF in December, they would start FT in January if the bank allowed it. If they finished the MSF in May, they would start FT in July like everybody else.

From how I am interpreting your situation, it seems you are going to graduate with your BS Finance degree, intern as as SA for a few months, and then come back to finish an MSF. Seems like a similar situation so no I don't think there is an issue.

For your last question on whether they would convert you straight to a FT Analyst, I don't think so. Banks consistently have a pipeline of hiring new grads because they expect Analysts to consistently leave every year after these Analysts are done with their 2nd year. If you are thinking you would finish your SA in August and then return a month later as a FT Analyst, I would say that is likely not going to happen. Ideally, these banks start you the following summer in July because they want to run you through a training program. Some people have the ability to start in January versus July, but that is case by case. I don't think starting before January following your SA stint at a BB is very negotiable though.