At this scale? Why don't you give some examples.

Pull our POV back far enough, and isn't "circular funding" just "The economy?"

Money circulates; it's what it does. The real question is to what extent circulation among a small group of firms is either collusion in disguise (i.e. decisionmaking by only one actual entity falsely measured as multiple independent entities) or a fragile ecosystem masquerading as a healthy one (i.e. an "island economy" where things look great in the current status quo, but the moment the fish go away the entire cycle instantly collapses).