From what I can remember what my friends are doing and did:
1 on grad programme doing fixed income at Deutsche Bank
1 on grad programme doing operations at JPMorgan
1 on grad programme doing audit at PWC
1 on grad programme doing acturial at Mercer
2 on grad programme doing audit at Deloitte
1 on grad programme doing corporate finance at KPMG
1 did internship at SEO (which helps ethnic minorities get jobs in Finance, Banking, IT and Law)
1 about to do training course to become a barrister (I don't remember the exact details lol)
Apart from the above, other factors make Soton great are league table rankings, quality of teaching, etc.