Soweit ich das verstehe, handelt es sich um Fonds, die von den Banken gehalten werden, s. die untenstehende Erklärung, die ich im Internet gefunden haben:
That means it's prime time for prime-rate funds. Also known as bank loan funds, these portfolios are comprised of loans made to corporate borrowers that are pegged to the prime lending rate, now 4%; the rates on the loans are usually prime plus 3% or so. That means the funds' yields rise along with rates".