No 'private' meaning that the transaction is between the lender and the borrower without a public rating agency involved (Moody's, etc...). This used to be for niche things like a data center where a rating agency might have trouble figuring out reasonable rating. Then the data center company would go to somebody like Apollo who could do custom analysis on the risk.

But now those private loans are being syndicated to affluent investors who probably don't understand that while some of this debt is solid, alot of it is not. And without a rating agency involved nobody knows how much risk is in there.