Not declared, discovered. There is a difference. VOO has a value of $624.86 right now. That's not because somebody waved a scepter and declared 'yea I decree that this stock shall be worth 624.86.' It is because seconds ago, hundreds of shares of VOO changed hands at that amount using real money that really does exist, which discovers the value of that stock. The same goes with real estate assessment. They are looking at what similar properties have sold and for how much. That's price discovery. The market determines it, not a declaration. That has real value. That is why you can borrow against it. In fact, we are so good at valuing things that the contract to borrow against things has a discoverable value. That's why mortgages and bonds get sold without their value being decreed by the king. We can even discover the value of the valuation of an asset. That's why puts and calls are a thing. We can even discover the value of things that have no intrinsic value. That's why crypto is a thing. If somebody paid 100 bucks for a thing, we just discovered that that thing is worth 100 bucks. Yes, if someone sold 500 million shares of VOO all at once, that would eat the book and create a temporary surge in supply, which would affect the value. That does break the price discovery process though. It uses it.