Financial Intermediary
  
Sometimes middlemen are blood-sucking-leech-level-annoying, and sometimes they’re a necessity. Likely an evil one.
A financial intermediary is a middleman in a financial transaction. Banks (commercial and investment) use financial intermediaries, as do funds (think: mutual, pension, etc.) before sealing the deal. For a small fee.
Why might you want a financial intermediary? Financial intermediaries usually know a lot more about risk, asset management, and investment banks than you do, so it’s no wonder they help banks and funds get their ducks in a row. In the same way that you’d probably want a lawyer in a court case, banks employ financial intermediaries for large financial transactions.
Their collective motto: "Check yoself before you wreck yoself."
See: Investment Banker. And Shmoop has a whole Wall Street Careers section on this lovely topic, should it tickle your commission bone.