On Interactive Brokers I can place limit orders for TVIX only to the nearest penny. But time and sales data from Nasdaq (see below) shows that some trades occur at fractional penny prices. If TVIX is quoted at 4.45 to 4.46, how can I try to buy at 4.455? time price volume 10:34:07 $ 4.46 760 10:34:07 $ 4.45 400 10:34:05 $ 4.45 400 10:33:50 $ 4.45 25,000 10:33:50 $ 4.455 500 10:33:50 $ 4.456 5,000
You may be able to put in a "midpoint" order on some exchanges and receive a fill at a half-penny increment; for example, IEX executes many of its orders at the midpoint. Other increments that are not at half-penny are probably "internalization" or "order flow sold to wholesalers", which is a nasty and growing problem. Most retail brokerages are selling client order flow in order to make a little extra profit for themselves, while costing their clients a colossal amount of money in bad/missed executions, all while trumpeting a trivial and deceptive "price improvement" of $.0001. http://www.nanex.net/aqck2/3519.html