If you go all the way back and disregard small fry like me, the ultimate big owners are often pension funds. Landed gentry it's not.
For most of these "are you nobility" questions, you can draw a line on a net worth chart where the incentives and privileges are one thing below the line and a different thing above the line. Each question gives you a different line, but for the most part you and I are on one side of the lines and, say, Bill Gates is on the other. It's important to understand that the world is mostly owned by people who feel a structurally different set of incentives from what you and I feel.
Further, I also don't think pension funds are similar to nobility. They have a lot of money and own a lot of buildings (indirectly through funds), but also a lot of future obligations to a lot of people who aren't any kind of nobility. Their assets don't add up to more than their obligations, certainly not to so much more that the difference can sustain a nobility.
The land belonging to an aristocrat can only go to another. Sales are regulated by the central government. Additionally, aristocrats have a de jure place in the government hierarchy, military rights, and the right to enforce laws on their own land.
Gentry are just rich people.
However being wealthy and having soft power via your wealth doesn’t make one a noble.
If a poor ”noble” isn’t still “worth” more than a rich commoner merchant in some circumstances then you don’t have a real class system.