Should a bank/financial service use external URL shortener services?

Say there is a bank/financial service that wants to have hyperlinks on their secure website/domain (or even in emails they send out to customers). In some of these links there are some long/obscure URLs which link to one of their subdomains, but the long links are ugly and not very user friendly, so they want to have shorter, nicer links to put on the website or email.

  • What are the risks for a bank/financial service using an external URL shortener service, e.g. Bitly, for this?
  • Is it better for a bank/financial service to host this sort of short link to long link translation service on their own domain and infrastructure?