Market-Maker Spread

She makes a market in GE. She owns 10 million shares and, as of this moment, she's a buyer at $15.23 and a seller at $15.29, making a 6-cent spread on those shares. On any given day, in the brokerage community with whom she deals, she trades about 4 million shares on average, making 6 cents on every trade. Her market-maker spread is 6 cents. And yeah, it's good work if you can get it.

See: Bid-Ask Spread.