I don't think that's right for all of them. I suspect it's the company that owns the lease or loan on a plane that's being financed. For example, the current first listing is an A319-112 with the number A997E5. According to PlaneFinder that's operated by American Airlines[0]. A lot of them are very large planes, which wouldn't really make sense for a private jet. Some are smaller, though, and are probably being financed by the ultra-wealthy.

0: https://planefinder.net/data/aircraft/N717UW