[dragonwriter]

> If I create a billion 'FOOCoins' and sell one to a friend for $1, FOOCoin now has a 1 billion market cap, but only a single dollar has changed hands. He sells it back to me for $2, now FOOCoin has a cap of $2 billion! With only $3 having changed hands.

Only $1 has changed hands in this.

[ceejayoz]

$1 changed hands, but the trading volume is $3.

There's a lot of speculation that this sort of "wash trading" happens in Bitcoin - some exchanges permit buying/selling to yourself, which lets someone boost both price and volume trivially.

[Nursie]

Well true, in aggregate. But we may have used up to three different notes :)