If you look at their latest 10Q they are basically a CEF that owns a lot of private loans & equity in non-public companies so its like a hybrid CLO + Venture Equity. 7.75% 5 year debt probably means they are A or AA.
Gladstone Capital is a business development company (BDC). A BDC is a specific type of closed-end fund. And yes, they hold equity and debt in companies that are not publicly traded. I'm not disputing what you said. But I would be pleasantly surprised if the GLADZ baby bonds get an investment-grade rating. Most bonds issued by BDCs are below investment grade. We hold regular bonds ($1000 face value) from several BDCs. They are all rated Baa3 or BBB-. I've attached some data.