than Pro-Rata. The reason is that market participants might want to place more small orders in different positions in the order queue, and also tend to “flood” the market, i.e., place limit order in the depth of the market in order to stay in the queue. Pro-Rata algorithm Motivates other orders to join the queue with large limit orders. As a consequence, the cumulative quoted volume at the best price is relatively large. Efficiency Large limit orders can be "front-run" by "penny jumping". For example, if a buy limit order for 100,000 shares for $1.00 is announced to the market, many traders may seek to buy for $1.01. If the market price increases after their purchases, they will get the full amount of the price increase. However, if the market price decreases, they will likely be able to sell to the limit order trader, for only a one cent loss. This type of trading is probably not illegal, and in any case, a law against it would be very difficult to enforce. See also Alternative trading system Dark pool Electronic communication network High-frequency trading Multilateral trading facility Open outcry References Financial markets