What will happen when a bid price is higher than an ask price?
It depends on the sequence in which the order [bid and ask] were placed. Please read the below question to understand how the order are matched. How do exchanges match limit orders? The situation you're proposing is an over-simplification that wouldn't occur in practice. Orders occur in a sequence over time. Time is an important part of the order matching process. Orders are not processed in parallel; otherwise, the problem of fairness, already heavily regulated, would become even more complex. First, crossed and locked markets are forbidden by regulators.  Crossed orders are where one exchange has a higher bid than another's ask, or a lower ask than another's bid.  A locked market is where a bid on one exchange is equal to the ask on another.  HFTs would be able to make these markets because of the gap between exchange fees. Since these are forbidden, and handling orders in parallel would ensure that a crossed or locked market would occur, orders are serialized (queued up), processed in order of price-time priority. So, the first to cross the market will be filled with the best oldest opposing order. Regulators believe crossed or locked markets are unfair.  They would however eliminate the bid ask spread for many large securities thus the bid-ask cost to the holder.
"Say we have stock XYZ that costs $50 this second. It doesn't cost XYZ this second. The market price only reflects the last price at which the security traded. It doesn't mean that if you'll get that price when you place an order. The price you get if/when your order is filled is determined by the bid/ask spreads. Why would people sell below the current price, and not within the range of the bid/ask? Someone may be willing to sell at an ask price of $47 simply because that's the best price they think they can sell the security for. Keep in mind that the ""someone"" may be a computer that determined that $47 is a reasonable ask price. Remember that bid/ask spreads aren't fixed, and there can be multiple bid/ask prices in a market at any given time. Your buy order was filled because at the time, someone else in the market was willing to sell you the security for the same price as your bid price. Your respective buy/sell orders were matched based on their price (and volume, conditional orders, etc). These questions may be helpful to you as well: Can someone explain a stock's ""bid"" vs. ""ask"" price relative to ""current"" price? Bids and asks in case of market order Can a trade happen ""in between"" the bid and ask price? Also, you say you're a day trader. If that's so, I strongly recommend getting a better grasp on the basics of market mechanics before committing any more capital. Trading without understanding how markets work at the most fundamental levels is a recipe for disaster." "If history is any guide, Page’s idealistic impulses could result in a vaster, more sprawling company. The following is an example of one of Page’s idealistic impulses (wanting people to share spectrum) which could result in a vaster, more sprawling company (if they hadn't been outbid, Google would have expanded by buying a business asset i.e. spectrum which they didn't need). I've no experience with bidding. I don't understand what's happening at all An 'auction' is a way to sell something. Instead of offering it for sale at a fixed price, you offer it 'to the highest bidder'. Someone (e.g. Google) says, ""I'll offer you [some amount: e.g. a million dollars] for it."" If no-one else exceeds that bid, then you say 'sold' and Google has bought it. Alternatively someone else comes along with a higher bid, ""I'll offer you two million dollars for it,"" in which case they're the new high bidder, and you'll sell it to them unless the process repeats itself with anyone counter-offering an even higher bid. See also http://en.wikipedia.org/wiki/Auction and http://en.wikipedia.org/wiki/Spectrum_auction The ""Disadvantages"" section of this article alleges (currently without a citation) that: Despite the apparent success of spectrum auctions, an important disadvantage limiting both efficiency and revenues is demand reduction and collusive bidding. The information and flexibility in the process of auction can be used to reduce auction prices by tacit collusion. When bidder competition is weak and one bidder holds an apparent advantage to win the auction for specific licenses, other bidders will often choose not to the bid for higher prices, hence reducing the final revenue generated by the auction.[citation needed] In this case, the auction is best thought of as a negotiation among the bidders, who agree on who should win the auction for each discrete bit of spectrum. Google's bid made that impossible (or, at least, ensured that the winning bid would be at least as high as the minimum which was set by Google's bid)." "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." "When I first started working in finance I was given a rule of thumb to decide which price you will get in the market: ""You will always get the worst price for your deal, so when buying you get the higher ask price and when selling you get the lower bid price."" I like to think of it in terms of the market as a participant who always buys at the lowest price they can (i.e. buys from you) and sells at the highest price they can. If that weren't true there would be an arbitrage opportunity and free money never exists for long." "There are no ""rules"" about how the price should act after an IPO, so there are no guarantee that a ""pop"" would appear at the opening day. But when an IPO is done, it's typically underpriced. On average, the shares are 10% up at the end of the first day after the IPO (I don't have the source that, I just remember that from some finance course). Also, after the IPO, the underwriter can be asked to support the trading of the share for a certain period of time. That is the so called stabilizing agent. They have few obligations like: This price support in often done by a repurchase of some of the shares of poorly performing IPO. EDIT: Informations about the overallotment pool. When the IPO is done, a certain number of client buy the shares issued by the company. The underwriter, with the clients, can decide to create an overallotment pool, where the clients would get a little more shares (hence ""overallotment""), but this time the shares are not issued by the company but by the underwriter. To put it another way, the underwriter oversell and becomes short by a certain number of shares (limited to 15% of the IPO). In exchange for the risk taken by this overallotment, the underwriter gets a greenshoe option from the clients, that will allows the underwriter to buy back the oversold shares, at the price of the IPO, from the clients. The idea behind this option is to avoid a market exposure for the underwriter. So, after the IPO: If the price goes down, the underwriter buys back on the market the overshorted shares and makes a profits. If the price goes up, the company exercise the greenshoe option buy the shares at the IPO prices (throught the overallotment pool, that is, the additional shares that the clients wanted ) to avoid suffering a loss." The price is moving higher so by the time you enter your order and press buy, a new buyer has already come in at that time and taken out the lowest ask price. So you end up chasing the market as the prices keep moving higher. The solution: if you really want to be sure that you buy it and don't want to keep chasing the market higher and higher, you should put in a market order instead of a limit order. With a market order you may pay a few cents higher than the last traded price but you will be sure to have your order filled. If you keep placing limit orders you may miss out altogether, especially if the price keeps moving higher and higher. In a fast moving market a market order is always best if your aim is to be certain to buy the stock. There isn't a formula like that, there is only the greed of other market participants, and you can try to predict how greedy those participants will be. If someone decided to place a sell order of 100,000 shares at $5, then you can buy an additional 100,000 shares at $5. In reality, people can infer that they might be the only ones trying to sell 100,000 shares right then, and raise the price so that they make more money. They will raise their sell order to $5.01, $5.02 or as high as they want, until people stop trying to buy their shares. It is just a non-stop auction, just like on ebay. That price is the post-tender price, which already reflects arbitrage.  It's less than $65 on the market because that's the highest offer out there and the market price reflects the risk that the $65 will not be paid.  It also reflects the time value of money until the cash is disbursed (including blows to liquidity). In other words, you are buying the stock burdened with the risk that it might rapidly deflate if the deal falls through (or gets revived at a lower price) or that your money might be better spent somewhere other than waiting for the i-bank to release the tender offer amount to you. Two months ago JOSB traded around $55, and four months ago it traded around $50.  If the deal fails, then you could be stuck either taking a big loss to get out of the stock or waiting months (or longer) in the hope that another deal will come along and pay $65 (which may leave you with NPV loss from today).  The market seems to think that risk is pretty small, but it's still there. If the payout is $65, then you get a discount for time value and a discount for failed-merger risk.  That means the price is less than $65.  You can still make money on it, if the merger goes through.  Some investors believe they have a better way to make money, and no doubt the tender offer of the incipient merger of two publicly traded companies is already heavily arbitraged.  But that said, it may still pay off. Tender offer arbitrage is discussed in this article.