Should a retail trader choose a broker with access to dark pools
"That's like a car dealer advertising their ""huge access"" to Chevrolet.  All brokers utilize dark pools nowadays, either their own or one belonging to a larger financial institution.  Why?  Because that's a primary source of broker income.  Example: Under current US regulations the broker is under no obligation to pass these orders to actual (a.k.a. lit) exchanges.  Instead it can internalize them in its dark pool as long as it ""improves the price"".  So: If a broker doesn't run its own dark pool, then it sends the orders to the dark pool run by a larger institution (JPMorgan, Credit Suisse, Getco, Knight Capital) and gets some fraction of the dark pool's profit in return. Are Mom and Pop negatively impacted by this?  Not for most order types.  They each even got a free penny out of the deal!  But if there were no dark pools, that $1.00 difference between their trade prices would have gone half ($0.50) to Mom's counterparty and half ($0.50) to Pop's counterparty, who could be someone else's Mom and someone else's Pop. So ... that's why brokers all use dark pools, and why their advertisement of their dark pool access is silly.  They're basically saying, ""We're going to occasionally throw you a free penny while making 49 times that much from you""! (Note: Now apply the above math to a less liquid product than AAPL.  Say, where the spread is not $0.01, but more like $0.05.  Now Mom and Pop still might make a penny each, while the broker can make $4.98 on a 100 share trade!)"
There are still human brokers on the floor primarily due to tradition. Their numbers have certainly dwindled, however, and it's reasonable to expect the number of floor traders to decrease even more as electronic trading continues to grow. A key reason for human brokers, however, is due to privacy. Certain private exchanges such as dark pools maintain privacy for high profile clients and institutional investors, and human brokers are needed to execute anonymous deals in these venues. Even in this region, however, technology is supplanting the need for brokers. I don't believe there is any human-broker-free stock exchange, but Nasdaq and other traditionally OTC (over the counter) exchanges are as close as it gets since they never even had trading floors. I don't know why a financial investor or a retail trader would do this. But I can guess why a market maker in options would do this. Let us say you buy an option from an option market maker and the market maker sold the option to you. He made a small profit in the bid-ask spread but now he is holding a short position in the option with unlimited risk exposure. So to protect himself, he will take an offsetting position in the underlying and become delta neutral, so that his position is not affected by the moves in the underlying. In the end, he can do this because he is not in the market to make money by betting on direction, unlike the rest of us poor mortals. He is making money from the bid-ask spread. So to ensure that his profits are not eroded by an adverse move in the underlying, he will continuously seek to be delta neutral. But once again, this is for a market maker. For market takers like us, I still don't understand why we would need to delta hedge. "Not arguing w that at all, and you can't colo w IB afaik. Their API over WAN, VPN or CTCI on direct line only. If you colo at Nasdaq and clear through Lightspeed you're talking microseconds (which is where my actual low latency strats are). But yes, I suppose for IB I should have mentioned ""low-ish"" latency rather than actual low latency. So I'll add a caveat to the newbs - don't try to do ECN arb (or any other super-low-latency strat) or market-make (their cancel fees will kill you) the entire equity universe through IB. It won't work. They're not suitable for that.  My 50-100 reference was for WAN IB clearing for these guys probably using their API through IB gateway or TWS, which is how most would likely start. Doubt they're diving head first into ECN arb day one - they probably wouldn't be doing lowest latency stuff, most peeps start w some sort of trend following strat in my exp and you can work on those timescales w those. Trying to give advice for people starting out, not for other already pro algo traders.  But yes, finprogger is correct, IB would not be a suitable broker to use for a competitive ultra low-latency strat. They are too slow." The broker will probably submit records to the IRS, so there isn't anonymity at that level... I was wondering what relations are between brokerage companies and exchanges? Are brokers representing investors to trade on exchanges? Yes...but a broker may also buy and sell stocks for his own account. This is called broker-delaer firm. For individual investors, what are some cons and pros of trading on the exchanges directly versus indirectly via brokers? Doesn't the former save the investors any costs/expenses paid to the brokers? Yes, but to trade directly on an exchange, you need to register with them. That costs money and only a limited number of people can register I believe. Note that some (or all?) exchanges have their websites where I think trading can be done electronically, such as NASDAQ and BATS? Can almost all stocks be found and traded on almost every exchange? In other words, is it possible that a popular stock can only be found and traded on one exchange, but not found on the other exchange? If needed to be more specific, I am particularly interested in the U.S. case,and for example, Apple's stock. Yes, it is very much possible with smaller companies. Big companies are usually on multiple exchanges. What are your advices for choosing exchange and choosing brokerage companies? What exchanges and brokerage companies do you recommend? For brokerage companies, a beginner can go with discount broker. For sophisticated investors can opt for full service brokers. Usually your bank will have a brokerage firm. For exchanges, it depends...if you are in US, you should send to the US exchanges. IF you wish to send to other exchanges in other countries, you should check with the broker about that. This. Everyone knows it is impossible for more than a handful of VERY well-funded hedge funds to actually run computerized trading operations that actually outperform the market significantly, and then that advantage is very difficult to defend.  Any hedge fund that just depends on traders that outperforms consistently is very likely to be cheating. If you want direct access trading that is very hard to get. However an active trading broker like interactive brokers, Trade station, or Light speed trading may be what you are looking for. If you have serious cash though value or income investing is better than trading which is pure speculation. I know that active trading can be exciting but it's also basically gambling when compared to research based long term investment. You can't fight the market makers, the guys on the dealer desks have way too many advantages over you. Just give this all some thought and see what you want to do. I will assume that you are not asking in the context of high frequency trading, as this is Personal Finance Stack Exchange. It is completely acceptable to trade odd lots for retail brokerage customers. The odd lot description that you provided in your link, from Interactive Brokers is correct. But even in that context, it says, regarding the acceptability of odd lots to stock exchanges: The exception is that odd lots can be routed to NYSE/ARCA/AMEX, but   only as part of a basket order or as a market-on-close (MOC) order. Google GOOG is traded on the NASDAQ. Everything on the NASDAQ is electronic, and always has been. You will have no problem selling or buying less than 100 shares of Google.  There is also an issue of higher commissions with odd lots: While trading commissions for odd lots may still be higher than for   standard lots on a percentage basis, the popularity of online trading   platforms and the consequent plunge in brokerage commissions means   that it is no longer as difficult or expensive for investors to   dispose of odd lots as it used to be in the past. Notice what it says about online trading making it easier, not more difficult, to trade odd lots. Yea that example is a little skewed when you made the aum differ by 200%. Those two candidates would never apply for the same role.  Networking is essential to get you looked at but at the end of the day it is still all about risk adjusted pnl.  Not to mention that pnl is really all you have to judge a trader I'd think that liquidity and speed are prioritized (even over retail brokers and in come cases over PoP) for institutional traders who by default have large positions.  When the going gets tough, these guys are out and the small guys - trading through average retail brokers - are the ones left holding the empty bag. Retail brokers and are generally not members of exchanges and would generally not be members of exchanges unless they are directly routing orders to those exchanges. Most retail brokers charging $7 are considered discount brokers and such brokers route order to Market Makers (who are members of the exchanges). All brokers and market makers must be members of FINRA and must pay FINRA registration and licensing fees.  Discount brokers also have operational costs which include the cost of their facilities, technology, clearing fees, regulation and human capital. Market makers will have the same costs but the cost of technology is probably much higher. Discount brokers will also have market data fees which they will have to pay to the exchanges for the right to show customer real time quotes.  Some of their fees can be offset through payment for order flow (POF) where market makers pay routing brokers a small fee for sending orders to them for execution. The practice of POF has actually allowed retail brokers to keep their costs lower but to to shrinking margins and spread market makers POF has significantly declined over the years.  Markets makers generally do not pass along Exchange access fees which are capped at $.003 (not .0035) to routing brokers.  Also note that The SEC and FINRA charges transactions fees. SEC fee for sales are generally passed along to customers and noted on trade confirms. FINRA TAF is born by the market makers and often subtracted from POF paid to routing firms. Other (full service brokers) charging higher commissions are charging for the added value of their brokers providing advice and expertise in helping investors with investment strategies. They will generally also have the same fees associated with membership of all the exchanges as they are also market makers subject to some of the list of cost mentioned above.  One point of note is that Market Making technology is quite sophisticates and very expensive.  It has driven most of wholesale market makers of the 90s into consolidation.    Retail routing firm's save a significant amount of money for not having to operate such a system (as well as worry about the regulatory headaches associated with running such a system).  This allows them to provide much lower commissions that the (full service) or bulge bracket brokers. I don't think that the trading volume would impact a broker's ability to find shares to short.  You might think that a lot more people are trying to short a stock during regular trading hours than in the pre-market, and that's probably true.  But what's also true is that a lot more people are covering their shorts during regular trading hours than in the pre-market.  For stocks that have difficulty in finding shares to short, any time someone covers a short is an opportunity for you to enter a short. If you want to short a stock and your broker is rejecting your order because they can't find shares to short, then I would recommend that you continue placing that order throughout the day.  You might get lucky and submit one of those orders right after someone else has covered their short and before anyone else can enter a short.  I have had success doing this in the past. "Yes.  I heard back from a couple brokerages that gave detailed responses. Specifically: In a Margin account, there are no SEC trade settlement rules, which means there is no risk of any free ride violations. The SEC has a FAQ page on free-riding, which states that it applies specifically to cash accounts. This led me to dig up the text on Regulation T which gives the ""free-riding"" rule in §220.8(c), which is titled ""90 day freeze"". §220.8 is the section on cash accounts. Nothing in the sections on margin accounts mentions such a settlement restriction. From the Wikipedia page on Free Riding, the margin agreement implicitly covers settlement. ""Buying Power"" doesn't seem to be a Regulation T thing, but it's something that the brokerages that I've seen use to state how much purchasing power a client has. Given the response from the brokerage, above, and my reading of Regulation T and the relevant Wikipedia page, proceeds from the sale of any security in a margin account are available immediately for reinvestment. Settlement is covered implicitly by margin; i.e. it doesn't detract from buying power. Additionally, I have personally been making these types of trades over the last year. In a sub-$25K margin account, proceeds are immediately available. The only thing I still have to look out for is running into the day-trading rules." API wise there's just one at the retail level: Interactive Brokers (India). Brokerage is high though - 3.5 bps for F&O and 5 bps for cash.  I've used Sharekhan (good, can get to 2 bps brokerage, trading client software, no API). Also used multiple other brokerages, and am advising a new one, Zerodha http://www.zerodha.com. API wise the brokers don't provide it easily to retail, though I've worked with direct access APIs at an institutional level. There are two terms that are related, but separate here: Broker and Market Maker.  The former is who goes and finds a buyer/seller to buy/sell shares from/to you.   The latter (Market Maker) is a company which will agree to partner with you to complete the sale at a set price (typically the market price, often by definition as the market maker often is the one who determines the market price in a relatively low volumne listing).  A market maker will have as you say a 'pool' of relatively common stock (and even relatively uncommon, up to a point) for this purpose. A broker can be a market maker (or work for one), also, in which case he would sell you directly the shares from the market maker reservoir.  This may be a bad idea for you - the broker (while obligated to act in your interest, in theory) may push you towards stocks that the brokerage acts as a market maker for.