Offer your thoughts or opinion on the input financial query or topic using your financial background.

The spread goes to the market maker, is the market maker the exchange?
Joke warning: These days, it seems that rogue trading programs are the big market makers (this concludes the joke) Historically, exchange members were market makers. One or more members guaranteed a market in a particular stock, and would buy whatever you wanted to sell (or vice-versa). In a balanced market -- one where there were an equal number of buyers and sellers -- the spread was indeed profit for them. To make this work, market makers need an enormous amount of liquidity (ability to hold an inventory of stocks) to deal with temporary imbalances. And a day like October 29, 1929, can make that liquidity evaporate. I say "historically," because I don't think that any stock market works this way today (I was discussing this very topic with a colleague last week, went to Wikipedia to look at the structure of the NYSE, and saw no mention of exchange members as market makers -- in fact, it appears that the NYSE is no longer a member-based exchange). Instead, today most (all?) trading happens on "electronic crossing networks," where the spread is simply the difference between the highest bid and lowest ask. In a liquid stock, there will be hundreds if not thousands of orders clustered around the "current" price, usually diverging by fractions of a cent. In an illiquid stock, there may be a spread, but eventually one bid will move up or one ask will move down (or new bids will come in). You could claim that an entity with a large block of stock to move takes the role of market maker, but it doesn't have the same meaning as an exchange market maker. Since there's no entity between the bidder and asker, there's no profit in the spread, just a fee taken  by the ECN. Edit: I think you have a misconception of what the "spread" is. It's simply the difference between the highest bid and the lowest offer. At the instant a trade takes place, the spread is 0: the highest bid equals the lowest offer, and the bidder and seller exchange shares for money. As soon as that trade is completed, the spread re-appears. The only way that a trade happens is if buyer and seller agree on price. The traditional market maker is simply an entity that has the ability to buy or sell an effectively unlimited number of shares. However, if the market maker sets a price and there are no buyers, then no trade takes place. And if there's another entity willing to sell shares below the market maker's price, then the buyers will go to that entity unless the market's rules forbid it.