Is it easier for brokers to find shares to short in premarket?
"The shares available to short are a portion of those shares held by the longs. This number is actually much easier to determine outside of active trading hours, but either way doesn't really impact the matter at hand since computers are pretty good at counting things. If your broker is putting up obstacles to your issuing sell short limit orders in the pre-market then there is likely some other reason (maybe they reserve that function to ""premium"" account holders?)" 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.
The advice I have is short and sweet. Be an investor, not a speculator. Adopt the philosophy of Warren Buffet which is the 'buy and hold' philosophy. Avoid individual stocks and buy mutual funds or ETFs. Pick something that pays dividends and reinvest those dividends. Don't become a speculator, meaning avoid the 'buy low, sell high' philosophy.  EDIT:For some reason I cannot add a comment, so I am putting my response here.  @jad The 'buy low, sell high' approach makes money for the stock broker, not necessarily you. As we learn in the movie Trading Places, each buy or sell creates a commission for the broker. It is those commission expenses that eat away at your nestegg. Just don't sell. If a security is trading at $10 a share and pays $0.25 a share each quarter then you are getting 10% ROI if you buy that security (and if it continues to pay $0.25 a share each quarter). If the price goes up then the ROI for new buyers will go down, but your ROI will still be the same. You will continue to get 10% for as long as you hold that security. A mutual fund buys the individual stocks for you. The value of the fund is only calculated at the end of the day. An ETF is like a mutual fund but the value of the ETF is calculated moment by moment. "Because ETFs, unlike most other pooled investments, can be easily shorted, it is possible for institutional investors to take an arbitrage position that is long the underlying securities and short the ETF.  The result is that in a well functioning market (where ETF prices are what they should be) these institutional investors would earn a risk-free profit equal to the fee amount. How much is this amount, though? ETFs exist in a very competitive market.  Not only do they compete with each other, but with index and mutual funds and with the possibility of constructing one's own portfolio of the underlying.  ETF investors are very cost-conscious. As a result, ETF fees just barely cover their costs.  Typically, ETF providers do not even do their own trading.  They issue new shares only in exchange for a bundle of the underlying securities, so they have almost no costs.  In order for an institutional investor to make money with the arbitrage you describe, they would need to be able to carry it out for less than the fees earned by the ETF.  Unlike the ETF provider, these investors face borrowing and other shorting costs and limitations. As a result it is not profitable for them to attempt this.  Note that even if they had no costs, their maximum upside would be a few basis points per year.  Lots of low-risk investments do better than that. I'd also like to address your question about what would happen if there was an ETF with exorbitant fees.  Two things about your suggested outcome are incorrect.   If short sellers bid the price down significantly, then the shares would be cheap relative to their stream of future dividends and investors would again buy them.  In a well-functioning market, you can't bid the price of something that clearly is backed by valuable underlying assets down to near zero, as you suggest in your question. Notice that there are limitations to short selling.  The more shares are short-sold, the more difficult it is to locate share to borrow for this purpose.  At first brokers start charging additional fees.  As borrowable shares become harder to find, they require that you obtain a ""locate,"" which takes time and costs money.  Finally they will not allow you to short at all.  Unlimited short selling is not possible. If there was an ETF that charged exorbitant fees, it would fail, but not because of short sellers.  There is an even easier arbitrage strategy: Investors would buy the shares of the ETF (which would be cheaper than the value of the underlying because of the fees) and trade them back to the ETF provider in exchange for shares of the underlying.  This would drain down the underlying asset pool until it was empty.   In fact, it is this mechanism (the ability to trade ETF shares for shares of the underlying and vice versa) that keeps ETF prices fair (within a small tolerance) relative to the underlying indices." This is a gross simplification as there are a few different ways to do this. The principle overall is the same though. To short a stock, you borrow X shares from a third party and sell them at the current price. You now owe the lender X shares but have the proceeds from the sale. If the share price falls you can buy back those shares at the new lower price, return them to the lender and pocket the difference. The risk comes when the share price goes the other way, you now owe the lender the new value of the shares, so have to find some way to cover the difference. This happened a while back when Porsche made a fortune buying shares in Volkswagen from short sellers, and the price unexpectedly rose. "Simplest way to answer this is that on margin, one is using borrowed assets and thus there are strings that come with doing that. Thus, if the amount of equity left gets too low, the broker has a legal obligation to close the position which can be selling purchased shares or buying back borrowed shares depending on if this is a long or short position respectively. Investopedia has an example that they walk through as the call is where you are asked to either put in more money to the account or the position may be closed because the broker wants their money back. What is Maintenance Margin? A maintenance margin is the required   amount of securities an investor must hold in his account if he either   purchases shares on margin, or if he sells shares short. If an   investor's margin balance falls below the set maintenance margin, the   investor would then need to contribute additional funds to the account   or liquidate stocks in the account to bring the account back to the   initial margin requirement. This request is known as a margin call. As discussed previously, the Federal Reserve Board sets the initial   margin requirement (currently at 50%). The Federal Reserve Board also   sets the maintenance margin. The maintenance margin, the amount of   equity an investor needs to hold in his account if he buys stock on   margin or sells shares short, is 25%. Keep in mind, however, that this   25% level is the minimum level set, brokerage firms can increase, but   not decrease this level as they desire. Example: Determining when a margin call would occur. Assume that an   investor had purchased 500 shares of Newco's stock. The shares were   trading at $50 when the transaction was executed. The initial margin   requirement on the account was 70% and the maintenance margin is 30%.   Assume no transaction costs. Determine the price at which the investor   will receive a margin call. Answer: Calculate the price as follows: $50 (1- 0.70) = $21.43 1 - 0.30 A margin call would be received when the price of Newco's stock fell   below $21.43 per share. At that time, the investor would either need   to deposit additional funds or liquidate shares to satisfy the initial   margin requirement. Most people don't want ""Margin Calls"" but stocks may move in unexpected ways and this is where there are mechanisms to limit losses, especially for the brokerage firm that wants to make as much money as possible. Cancel what trade? No, the broker will close the position if the requirement isn't kept. Basically think of this as a way for the broker to get their money back if necessary while following federal rules. This would be selling in a long position or buying in a short sale situation. The Margin Investor walks through an example where an e-mail would be sent and if the requirement isn't met then the position gets exited as per the law." I don't think that you will be able to find a list of every owner for a given stock. There are probably very few people who would know this. One source would be whoever sends out the shareholder meeting mailers.  I suspect that the company itself would know this, the exchange to a lesser extent, and possibly the brokerage houses to a even lesser extent. Consider these resources: Yes in order for you to short a stock, some one has to be willing to lend it to you to short, the more people that want to short this stock, the higher the borrowing rate is to short it. in some instances such as groupon so many people are shorting it that there are practically no shares left to short and if you do end up getting some it would be at a very high borrowing cost. "Brokerages offer you the convenience of buying and selling financial products. They are usually not exchanges themselves, but they can be. Typically there is an exchange and the broker sends orders to that exchange. The main benefit that brokers offer is a simpler commission structure. Not all brokers have their own liquidity, but brokers can have their own allotment of shares of a stock, for example, that they will sell you when you make an order, so that you get what you want faster. Regarding accounts at the exchanges to track actual ownership and transfer of assets, it is not safe to assume thats how that works. There are a lot of shortcomings in how the actual exchange works, since the settlement time is 1 - 3 business days, depending on the product (so upwards of 5 to 6 actual days). In a fast market, the asset can change hands many many times making the accounting completely incorrect for extended time periods. Better to not worry about that part, but if you'd like to read more about how that is regulated look up ""Failure To Deliver"" regulations on short selling to get a better understanding of market microstructure. It is a very antiquated system." It's not necessarily the case that HFT acts as a tax on small traders. I haven't seen any studies demonstrating that HFT increases the average cost of shares; if anything small investors will be largely unaffected by HFT as it will be random noise to them, sometimes creating a slight increase, sometimes a slight decrease. The people most affected by HFT are institutional investors, whom HFT desks are pretty good at predicting the order pattern of and hence exploiting. They have no interest or capacity to exploit the small guys.