I am not sure about this but I think that these prices depend most on what people think about the future.
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You are almost right.
When people think other people think a stock will rise and buy it, the price goes up.
When people think other people think that a stock will decline, the price will drop.
Prices do not depend on what people think: they depend on what people think other people will think.
I buy GLD at $129.73 because I think that at a future date not too far off, someone will be willing to pay $150 (or some price above the purchase price) for it. It is not because I get my jollies knowing that somewhere at Schwab, a computer credits my account with shares of GLD.
Most stock has something like "value $.10 per share" written on it.
Success in the market depends on being able to correctly guess what other people think about the value of a share, an option, a bond, a put or a call.