Last trade is bought? or sold?
"When there is a trade the shares were both bought and sold. In any trade on the secondary market there has to be both a buyer and a seller for the trade to take place. So in ""lasttradesize"" a buyer has bought the shares from a seller."
"Assuming that no one else has hit the ask, and the asks are still there, yes, you will fill $54.55 as long as you didn't exhaust that ask. Actually, there is no ""current price at which the stock is exchanging hands""; in reality, it is ""the last price traded"". The somebody who negotiated prices between buyers & sellers is the exchange through their handling of bids & asks.  The real negotiation comes between bids & asks, and if they meet or cross, a trade occurs. It's not that both bid & ask should be $54.55, it's that they were. To answer the title, the reasons why the bid and ask (even their midpoint) move away from the last price are largely unknown, but at least for the market makers, if their sell inventory is going away (people are buying heavily and they're running out of inventory) they will start to hike up their asks a lot and their bids a little because market makers try to stay market neutral, having no opinion on whether an asset will rise or fall, so with stocks, that means having a balanced inventory of longs & shorts.  They want to (sometimes have to depending on the exchange) accommodate the buying pressure, but they don't want to lose money, so they simply raise the ask and then raise the bid as people hit their asks since their average cost basis has risen. In fact (yahoo finance is great about showing this), there's rarely 1 bid and 1 ask.  Take a look at BAC's limit book: http://finance.yahoo.com/q/ecn?s=BAC+Order+Book You can see that there are many bids and many asks.  If one ask is exhausted, the next in line is now the highest.  The market maker who just sold at X will certainly step over the highest bid to bid at X*0.9 to get an 11% return on investment." The same as when you are buying a car. If a dealer quotes 10k and you quote 8k. 8k is the buy price and 10k is the sell price.  Somebody might quote 8.5k and another dealer might quote 9.5k. The the new price that you see on your screen is 8.5k(Best buy price) and 9.5k(Best sell price). When the buyer and seller agree to an amount, the car(In your case stock) is traded. From your question, I am guessing that you are intending to have stoploss buy order. is the stoploss order is also a buy order ?  As you also said, you seems to limit your losses, I am again guessing that you have short position of the stock, to which you are intending to place a buy limit order and buy stoploss order (stoploss helps when when the price tanks). And also I sense that you intend to place buy limit order at the price below the market price. is that the situation?  If you place two independent orders (one limit buy and one stoploss buy). Please remember that there will be situation where two orders also get executed due to market movements. Add more details to the questions. it helps to understand the situation and others can provide a strategic solution. In order to see whether you can buy or sell some given quantity of a stock at the current bid price, you need a counterparty (a buyer) who is willing to buy the number of stocks you are wishing to offload. To see whether such a counterparty exists, you can look at the stock's order book, or level two feed. The order book shows all the people who have placed buy or sell orders, the price they are willing to pay, and the quantity they demand at that price. Here is the order book from earlier this morning for the British pharmaceutical company, GlaxoSmithKline PLC.  Let's start by looking at the left-hand blue part of the book, beneath the yellow strip. This is called the Buy side. The book is sorted with the highest price at the top, because this is the best price that a seller can presently obtain. If several buyers bid at the same price, then the oldest entry on the book takes precedence. You can see we have five buyers each willing to pay 1543.0 p (that's 1543 British pence, or £15.43) per share. Therefore the current bid price for this instrument is 1543.0. The first buyer wants 175 shares, the next, 300, and so on. The total volume that is demanded at 1543.0p is 2435 shares. This information is summarized on the yellow strip: 5 buyers, total volume of 2435, at 1543.0. These are all buyers who want to buy right now and the exchange will make the trade happen immediately if you put in a sell order for 1543.0 p or less. If you want to sell 2435 shares or fewer, you are good to go. The important thing to note is that once you sell these bidders a total of 2435 shares, then their orders are fulfilled and they will be removed from the order book. At this point, the next bidder is promoted up the book; but his price is 1542.5, 0.5 p lower than before. Absent any further changes to the order book, the bid price will decrease to 1542.5 p. This makes sense because you are selling a lot of shares so you'd expect the market price to be depressed. This information will be disseminated to the level one feed and the level one graph of the stock price will be updated. Thus if you have more than 2435 shares to sell, you cannot expect to execute your order at the bid price in one go. Of course, the more shares you are trying to get rid of, the further down the buy side you will have to go. In reality for a highly liquid stock as this, the order book receives many amendments per second and it is unlikely that your trade would make much difference. On the right hand side of the display you can see the recent trades: these are the times the trades were done (or notified to the exchange), the price of the trade, the volume and the trade type (AT means automatic trade).  GlaxoSmithKline is a highly liquid stock with many willing buyers and sellers. But some stocks are less liquid. In order to enable traders to find a counterparty at short notice, exchanges often require less liquid stocks to have market makers. A market maker places buy and sell orders simultaneously, with a spread between the two prices so that they can profit from each transaction. For instance Diurnal Group PLC has had no trades today and no quotes. It has a more complicated order book, enabling both ordinary buyers and sellers to list if they wish, but market makers are separated out at the top. Here you can see that three market makers are providing liquidity on this stock, Peel Hunt (PEEL), Numis (NUMS) and Winterflood (WINS). They have a very unpalatable spread of over 5% between their bid and offer prices. Further in each case the sum total that they are willing to trade is 3000 shares. If you have more than three thousand Dirunal Group shares to sell, you would have to wait for the market makers to come back with a new quote after you'd sold the first 3000. You don't see Buying and Selling. You see Bid and Ask. Best Bid--Highest Price someone is willing to pay to buy a stock. Best Ask - Lowest price someone is willing to accept to sell a stock. As for your second question, if you can look up Accumulation/Distribution Algorithm and Iceberg Order, you will get basic idea. Market price simply depends on your order side.  If you are placing a buy order the market price is the lowest ask, if you are placing a sell order the market price is the highest bid.  If your order is larger than the volume then you'd need to also consider the next lowest ask or next highest bid until you've fulfilled your order volume. "You might consider learning how the ""matching"" or ""pairing"" system in the market operates.  The actual exchange only happens when both a buyer and a seller overlap their respect quotes.   Sometimes orders ""go to market"" for a particular volume.  Eg get me 10,000 Microsoft shares now.  which means that the price starts at the current lowest seller, and works up the price list until the volume is met.  Like all market it trades, it has it's advantages, and it's dangers.  If you are confident Microsoft is going to bull, you want those shares now, confident you'll recoup the cost.  Where if you put in a priced order, you might get only none or some shares. Same as when you sell.  If you see the price (which is the price of the last completed ""successful"" trade.  and think ""I'm going to sell 1000 shares"". then you give the order to the market (or broker), and then the same as what happened as before.  the highest bidder gets as much as they asked for, if there's still shares left over, they go to the next bidder, and so on down the price... and the last completed ""successful"" trade is when your last sale is made at the lowest price of your batch. If you're selling, and selling 100,000 shares. And the highest bidder wants 1,000,000 shares you'll only see the price drop to that guys bid.  Why will it drop (off the quoted price?).  Because the quoted price is the LAST sale, clearly if there's someone still with an open bid on the market...then either he wants more shares than were available (the price stays same), or his bid wasn't as high as the last bid (so when you sale goes through, it will be at the price he's offering).   Which is why being able to see the price queues is important on large traders. It is also why it can be important put stops and limits on your trades, een through you can still get gapped if you're unlucky.  However putting prices (""Open Orders"" vs ""(at)Market Orders"") can mean that you're sitting there waiting for a bounce/spike while the action is all going on without you). safer but not as much gain (maybe ;) ) that's the excitement of the market, for every option there's advantages...and risks... (eg missing out) There are also issues with stock movement, shadowing, and stop hunting, which can influence the price. But the stuff in the long paragraphs is the technical reasons." "In the United States, regulation of broker dealer credit is dictated by Regulation T, that for a non-margin account, 100% of a trade must be funded. FINRA has supplemented that regulation with an anti-""free rider"" rule, Rule 4210(f)(9), which reads No member shall permit a customer (other than a broker-dealer or a “designated     account”) to make a practice, directly or indirectly, of effecting transactions in a cash     account where the cost of securities purchased is met by the sale of the same securities.     No member shall permit a customer to make a practice of selling securities with them in a     cash account which are to be received against payment from another broker-dealer where     such securities were purchased and are not yet paid for. A member transferring an     account which is subject to a Regulation T 90-day freeze to another member firm shall     inform the receiving member of such 90-day freeze. It is only funds from uncleared sold equities that are prohibited from being used to purchase securities. This means that an equity in one's account that is settled can be sold and can be purchased only with settled funds.  Once the amount required to purchase is in excess of the amount of settled funds, no more purchases can be made, so an equity sold by an account with settled funds can be repurchased immediately with the settled funds so long as the settled funds can fund the purchase. Margin A closed position is not considered a ""long"" or ""short"" since it is an account with one loan of security and one asset of security and one cash loan and one cash liability with the excess or deficit equity equal to any profit or loss, respectively, thus unexposed to the market, only to the creditworthiness of the clearing & settling chain. Only open positions are considered ""longs"" or ""shorts"", a ""long"" being a possession of a security, and a ""short"" being a liability, because they are exposed to the market. Since unsettled funds are not considered ""longs"" or ""shorts"", they are not encumbered by previous trades, thus only the Reg T rules apply to new and current positions. Cash vs Margin A cash account cannot purchase with unsettled funds.  A margin account can.  This means that a margin account could theoretically do an infinite amount of trades using unsettled funds.  A cash account's daily purchases are restricted to the amount of settled funds, so once those are exhausted, no more purchases can be made. The opposite is true for cash accounts as well.  Unsettled securities cannot be sold either. In summation, unsettled assets can not be traded in a cash account." "As others have noted, your definition of ""market price"" is a bit loose.  Really whatever price you get becomes the current market price.  What you usually get quoted are the current best bid and ask with the last transaction price.  For stocks that don't trade much, the last transaction price may not be representative of the current market value. Your question included regulation (""standards bureau""), and I don't think the current answers are addressing that.  In the US, the Securities and Exchange Commission (SEC) provides some regulation regarding execution price.  It goes by the designation Regulation NMS, and, very roughly, it says that each transaction has to take the best available price at the time that it is executed.  There are some subtleties, but that's the gist of it. No regulation ensures that there will be a counterparty to any transaction that you want to make.  It could happen, for example, that you have shares of some company that you're never able to sell because no one wants them. (BitCoin is the same in this regard.  There is a currently a market for BitCoin, but there's no regulation that ensures there will be a market for it tomorrow.) Outside of the US, I don't know what regulation, if any, exists." In the world of stock exchanges, the result depends on the market state of the traded stock. There are two possibilities, (a) a trade occurs or (b) no trade occurs. During the so-called auction phase, bid and ask prices may overlap, actually they usually do. During an open market, when bid and ask match, trades occur. "A straddle is an options strategy in which one ""buys"" or ""sells"" options of the same maturity (expiry date) that allow the ""buyer"" or ""seller"" to profit based on how much the price of the underlying security moves, regardless of the direction of price movement. IE: A long straddle would be: You buy a call and a put at the same strike price and the same expiration date. Your profit would be if the underlying asset(the stock) moves far enough down or up(higher then the premiums you paid for the put + call options) (In case, one waits till expiry) Profit = Expiry Level - Strike Price - (Premium Paid for Bought Options) Straddle" "This is a misconception. One of the explanations is that if you buy at the ask price and want   to sell it right away, you can only sell at the bid price. This is incorrect. There are no two separate bid and ask prices. The price you buy (your ""bid"") is the same price someone else sells (their ""sell""). The same goes when you sell - the price you sell at is the price someone else buys. There's no spread with stocks. Emphasized it on purpose, because many people (especially those who gamble on stock exchange without knowing what they're doing) don't understand how the stock market works. On the stock exchange, the transaction price is the match between the bid price and the ask price. Thus, on any given transaction, bid always equals ask. There's no spread. There is spread with commodities (if you buy it directly, especially), contracts, mutual funds and other kinds of brokered transactions that go through a third party. The difference (spread) is that third party's fee for assuming part of the risk in the transaction, and is indeed added to your cost (indirectly, in the way you described). These transactions don't go directly between a seller and a buyer. For example, there's no buyer when you redeem some of your mutual fund - the fund pays you money. So the fund assumes certain risk, which is why there's a spread in the prices to invest and to redeem. Similarly with commodities: when you buy a gold bar - you buy it from a dealer, who needs to keep a stock. Thus, the dealer will not buy from you at the same price: there's a premium on sale and a discount on buy, which is a spread, to compensate the dealer for the risk of keeping a stock." "This is called ""change"" or ""movement"" - the change (in points or percentage) from the last closing value. You can read more about the ticker tape on Investopedia, the format you're referring to comes from there." "Buying (or selling) a futures contract means that you are entering into a contractual agreement to buy (or sell) the contracted commodity or financial instrument in the contracted amount (the contract size) at the price you have bought (or sold) the contract on the contract expire date (maturity date).  It is important to understand that futures contracts are tradeable instruments, meaning that you are free to sell (or buy back) your contract at any time before the expiry date. For example, if you buy 1 ""lot"" (1 contract) of a gold future on the Comex exchange for the contract month of December 2016, then you entering into a contract to buy 100 ounces (the contract size) of gold at the price at which you buy the contract - not the spot price on the day of expiry when the contract comes to maturity.  The December 2016 gold futures contract has an expiry date of 28 December.  You are free to trade this contract at any time before its expiry by selling it back to another market participant.  If you sell the contract at a price higher than you have purchased it, then you will realise a profit of 100 times the difference between the price you bought the contract and the price you sold the contract, where 100 is the contract size of the gold contract.  Similarly, if you sell the contract at a price lower than the price you have purchased it, then you will realise a loss. (Commissions paid will also effect your net profit or loss). If you hold your contract until the expiry date and exercise your contract by taking (or making) delivery, then you are obliged to buy (or sell) 100 ounces of gold at the price at which you bought (or sold) the contract - not the current spot price. So long as your contract is ""open"" (i.e., prior to the expiry date and so long as you own the contract) you are required to make a ""good faith deposit"" to show that you intend to honour your contractual obligations.  This deposit is usually called ""initial margin"".  Typically, the initial margin amount will be about 2% of the total contract value for the gold contract.  So if you buy (or sell) one contract for 100 ounces of gold at, say, $1275 an ounce, then the total contract value will be $127,500 and your deposit requirement would be about $2,500.  The initial margin is returned to you when you sell (or buy) back your futures contract, or when you exercise your contract on expiry. In addition to initial margin, you will be required to maintain a second type of margin called ""variation margin"".  The variation margin is the running profit or loss you are showing on your open contract. For the sake of simplicity, lets look only at the case where you have purchased a futures contract.  If the futures price is higher than your contract (buy) price, then you are showing a profit on your current position and this profit (the variation margin) will be used to offset your initial margin requirement. Conversely, if the futures price has dropped below your contracted (buy) price, then you will be showing a loss on your open position and this loss (the variation margin) will be added to your initial margin and you will be called to put up more money in order to show good faith that you intend to honour your obligations.  Note that neither the initial margin nor the variation margin are accounting items.  In other words, these are not postings that are debited or credited to the ledger in your trading account.  So in some sense ""you don't have to pay anything upfront"", but you do need to put up a refundable deposit to show good faith." If you are solvent enough, and organised enough to pay your credit card bill in full each month, then use the credit card.  There are no disadvantages and several plus points, already mentioned. Use the debit card when you would be surcharged for using the credit card, or where you can negotiate a discount for not subjecting the vendor to credit card commission.