In stock trading, a commitment by the market maker to find the highest price for a seller's shares, or the lowest price for a buyer, that is available in any market at that time.
The centerpiece of a complex new rule that the Securities and Exchange Commission is considering imposing on all stock markets at its Dec. 15 meeting.
An extension and modification of the SEC's current "trade through" rule, which now channels significant trading volume to the New York Stock Exchange.
A step that would give buyers and sellers simultaneous electronic access to all U.S. markets trading a particular stock.
A rule that could require market makers to post all bid and asked prices, making markets more transparent and liquid.
A compromise that would allow institutional investors to complete trades more quickly but make it harder for them to camouflage their trading strategies.