How much money was invested into Gamestop over the last two weeks?

Gamestop is at a $16B market cap now. Up from less the $2B a month ago. I wonder how much money had to be invested into it to get it to that level.

Everyone says retail investors reading Reddit are such a force now that it can move the needle on a stock. But how much money does it actually need to move a needle from $2B to $16B? For all I know it could have been a single share that has been traded back and forth from one pocket to the other of a loner in Gelsenkirchen.

Anybody here with more insights on how to estimate the real amount of money that was invested?