Order Protection Rule

The “Order Protection Rule,” also called “Rule 611,” or the “trade-through rule,” basically says that investors should receive the same price for a given security regardless of which exchange they’re trading on.

Makes sense, right? We don’t want to pay more—or get less—than another investor for the same stock, just because we’re looking at different exchanges. This rule applies to all NMS stocks (basically all stocks on the NASDAQ and other U.S. exchanges), and it’s been in effect since 2005.