Are stocks always able to be bought and sold at market price?
In general stock markets are very similar to that, however, you can also put in limit orders to say that you will only buy or sell at a given price. These sit in the market for a specified length of time and will be executed when an order arrives that matches the price (or better). Traders who set limit orders are called liquidity (or price) makers as they provide liquidity (i.e. volume to be traded) to be filled later. If there is no counterparty (i.e. buyer to your seller) in the market, a market maker; a large bank or brokerage who is licensed and regulated to do so, will fill your order at some price. That price is based on how much volume (i.e. trading) there is in that stock on average. This is called average daily volume (ADV) and is calculated over varying periods of time; we use ADV30 which is the 30 day average. You can always sell stocks for whatever price you like privately but a market order does not allow you to set your price (you are a price taker) therefore that kind of order will always fill at a market price. As mentioned above limit orders will not fill until the price is hit but will stay on book as long as they aren't filled, expired or cancelled. "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." Many of the Bitcoin exchanges mimic stock exchanges, though they're much more rudimentary offering only simple buy/sell/cancel orders.  It's fairly normal for retail stock brokerage accounts to allow other sorts of more complex orders, where once a certain criteria is met, (the price falls below some $ threshold, or has a movement greater than some %) then your order is executed.  The space between the current buy order and the current sell order is the bid/ask spread, it's not really about timing.  Person X will buy at $100, person Y will sell at $102.  If both had a price set at $101, they would just transact.  Both parties think they can do a little bit better than the current offer.  The width of the bid/ask spread is not universal by any means.  The current highest buy order and the current lowest sell order, are both the current price.  The current quoted market price is generally the price of the last transaction, whether it's buy or sell. "For any large company, there's a lot of activity, and if you sell at ""market"" your buy or sell will execute in seconds within a penny or two of the real-time ""market"" price.  I often sell at ""limit"" a few cents above market, and those sell within 20 minutes usually.  For much smaller companies, obviously you are beholden to a buyer also wanting that stock, but those are not on major exchanges.  You never see whose buy order you're selling into, that all happens behind the curtain so to speak." "There needs to be a buyer of the shares you are offering.  There are a lot of feature rich options for buying and selling.  I don't understand them all in depth, but for example on TD Ameritrade here are some of the order types ""Limit"", ""Market"", ""Stop Market"", ""Stop Limit"", ""Trailing Stop %"", ""Trailing Stop $"".  This web page will explain the different order types https://invest.ameritrade.com/cgi-bin/apps/u/PLoad?pagename=tutorial/orderTypes/overview.html Stock with a higher volume will allow your trade to execute faster, since there are more frequent trades than stocks with lower volume. (UPDATE: More specifically, not more frequent trades, but more shares changing hands.) I'm a bit of a noob myself, but that's what I understand."
This question is impossible answer for all markets but there are 2 more possibilities in my experience: 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. 1) Yes, both of your scenarios would lead to earning $10 on the transaction, at the strike date. If you purchased both of them (call it Scenario 3), you would make $20. 2) As to why this transaction may not be possible, consider the following: The Call and Put pricing you describe may not be available. What you have actually created is called 'arbitrage' - 2 identical assets can be bought and sold at different prices, leading to a zero-risk gain for the investor. In the real marketplace, if an option to buy asset X in January cost $90, would an option to sell asset X in January provide $110?  Without adding additional complexity about the features of asset x or the features of the options, buying a Call option is the same as selling a Put option [well, when selling a Put option you don't have the ability to choose whether the option is exercised, meaning buying options has value that selling options does not, but ignore that for a moment]. That means that you have arranged a marketplace where you would buy a Call option for only $90, but the seller of that same option would somehow receive $110.  For added clarity, consider the following: What if, in your example, the future price ended up being $200? Then, you could exercise your call option, buying a share for $90, selling it for $200, making $110 profit. You would not exercise your put option, making your total profit $110. Now consider: What if, in your example, the future price ended up being $10? You would buy for $10, exercise your put option and sell for $110, making a profit of $100. You would not exercise your call option, making your total profit $100. This highlights that if your initial assumptions existed, you would earn money (at least $20, and at most, unlimited based on a skyrocketing price compared to your $90 put option) regardless of the future price. Therefore such a scenario would not exist in the initial pricing of the options. Now perhaps there is an initial fee involved with the options, where the buyer or seller pays extra money up-front, regardless of the future price. That is a different scenario, and gets into the actual nature of options, where investors will arrange multiple simultaneous transactions in order to limit risk and retain reward within a certain band of future prices.  As pointed out by @Nick R, this fee would be very significant, for a call option which had a price set below the current price. Typically, options are sold 'out of the money' initially, which means that at the current share price (at the time the option is purchased), executing the option would lose you money. If you purchase an 'in the money' option, the transaction cost initially would by higher than any apparent gain you might have by immediately executing the option. For a more realistic Options example, assume that it costs $15 initially to buy either the Call option, or the Put option. In that case, after buying both options as listed in your scenarios you would earn a profit if the share price exceeded $120 [The $120 sale price less the $90 call option = $30, which is your total fee initially], or dropped below $80 [The $110 Put price less the $80 purchase price = $30]. This type of transaction implies that you expect the price to either swing up, or swing down, but not fall within the band between $80-$120. Perhaps you might do this if there was an upcoming election or other known event, which might be a failure or success, and you think the market has not properly accounted for either scenario in advance. I will leave further discussion on that topic [arranging options of different prices to create specific bands of profitability / loss] to another answer (or other questions which likely already exist on this site, or in fact, other resources), because it gets more complicated after that point, and is outside the root of your question. No, Mark is right, if you place a market order there will always be someone to buy or sell at the market price.  Only if you place a limit order on the price can it not sell or be bought.  Just research on your computer and you will find your answer.  You must be specify about open order or limit order when asking. Yes traders, living or algorithmic, are the only direct factors that can cause a change in the price of a marketable item. Traders can be affected by news, broken exchanges ;), emotional cycles, lunar cycles, time the trader goes to lunch (or a power cycle if you are an algo running on that unfortunate OS), anything. Yes you can, provided if buyers are available.  Normally high liquidty stocks can be sold at market prices a little higher or lower. It depends completely on the current order book for that security.  There is literally no telling how that buy order would move the price of a stock in general. If the share is listed on a stock exchange that creates liquidity and orderly sales with specialist market makers, such as the NYSE, there will always be a counterparty to trade with, though they will let the price rise or fall to meet other open interest.  On other exchanges, or in closely held or private equity scenarios, this is not necessarily the case (NASDAQ has market maker firms that maintain the bid-ask spread and can do the same thing with their own inventory as the specialists, but are not required to by the brokerage rules as the NYSE brokers are).  The NYSE has listing requirements of at least 1.1 million shares, so there will not be a case with only 100 shares on this exchange. "A market sell order will be filled at the highest current ""bid"" price. For a reasonably liquid stock, there will be several buy orders in line, and the highest bid must be filled first, so there should a very short time between when you place the order and when it is filled.   What could happen is what's called front running. That's when the broker places their own order in front of yours to fulfill the current bid, selling their own stock at the slightly higher price, causing your sale to be filled at a lower price.  This is not only unethical but illegal as well. It is not something you should be concerned about with a large broker.   You should only place a market order when you don't care about minute differences between the current ask and your execution price, but want to guarantee order execution. If you absolutely have to sell at a minimum price, then a limit order is more appropriate, but you run the risk that your limit will not be reached and your order will not be filled. So the risk is a tradeoff between a guaranteed price and a guaranteed execution." What you have to remember is that Options are derivatives of another asset like stocks for example.  The price of the Option is derived from the price of the underlying. If the underlying is a stock for example, as the price of the stock moves up and down during the trading day, so will the Market Maker's fair value for the Option.  As Options are usually less liquid than the underlying stock, Market Makers are usually more active in 'Providing a Market' with Options. Thus if you place a limit order half way between the current Bid and Ask and the underlying stock price moves towards your limit order, the Market Maker will do their job and 'Provide a Market' at that price, thus executing your order. "There are a few people that do this for a living. They are called ""market makers"" or ""specialists"" in a particular stock. First of all, this requires a lot of capital. You can get burned on a few trades, a process known as ""gambler's ruin,"" but if you have enough capital to weather the storm, you can make money. Second, you have to be ""licensed"" by the stock market authorities, because you need to have stock market trading experience and other credentials. Third, you are not allowed to buy and sell at will. In order to do your job, you have to ""balance the boat,"" that is buy, when others are selling, and sell, when others are buying, in order to keep the market moving in two directions. It's a tough job that requires a lot of experience, plus a license, but a few people can make a living doing this." "Price is decided by what shares are offered at what prices and who blinks first.  The buyer and seller are both trying to find the best offer, for their definition of best, within the constraints then have set on their bid or ask. The seller will sell to the highest bid they can get that they consider acceptable. The buyer will buy from the lowest offer they can get that they consider acceptable. The price -- and whether a sale/purchase happens at all -- depends on what other trades are still available and how long you're willing to wait for one you're happy with, and may be different on one share than another ""at the same time"" if the purchase couldn't be completed with the single best offer and had to buy from multiple offers. This may have been easier to understand in the days of open outcry pit trading, when you could see just how chaotic the process is... but it all boils down to a high-speed version of seeking the best deal in an old-fashioned marketplace where no prices are fixed and every sale requires (or at least offers the opportunity for) negotiation. ""Fred sells it five cents cheaper!"" ""Then why aren't you buying from him?"" ""He's out of stock."" ""Well, when I don't have any, my price is ten cents cheaper."" ""Maybe I won't buy today, or I'll buy elsewhere. ""Maybe I won't sell today. Or maybe someone else will pay my price. Sam looks interested..."" ""Ok, ok. I can offer two cents more."" ""Three. Sam looks really interested."" ""Two and a half, and throw in an apple for Susie."" ""Done."" And the next buyer or seller starts the whole process over again. Open outcry really is just a way of trying to shop around very, very, very fast, and electronic reconciliation speeds it up even more, but it's conceptually the same process -- either seller gets what they're asking, or they adjust and/or the buyer adjusts until they meet, or everyone agrees that there's no agreement and goes home." Depends on when you are seeing these bids & asks-- off hours, many market makers pull their bid & ask prices entirely.  In a lightly traded stock there may just be no market except during the regular trading day. You can always trade at bid or ask price (depending if you are selling or buying). Market price is the price the last transaction was executed at so you may not be able to get that. If your order is large then you may not even be able to get bid/ask but should look at the depth of the order book (ie what prices are other market participants asking for and what is the size of their order). Usually only fast traders will trade at bid/ask, those who believe the price move is imminent. If you are a long term trader you can often get better than bid or ask by placing a limit order and waiting until a market participant takes your offer. I've considered just calling the out-of-network hospital and asking   them to reduce the charges. Ideally they would send my health   insurance provider a smaller bill which I could just pay. However I   want to be careful about how I proceed. Yes, that's what you should be doing. They might give you a discount, but even if not - they will definitely be willing to work out a payment plan for you so that you could pay in installments and not in a lump sum. I have experience with the El Camino group in California, that did just that. It was several hundreds, so they didn't give a discount, but were able to work out an installment plan for several months without much hassle. That is something to do before you get to lawyers. I'm not sure I know how the lawyer could be useful to you, other than claiming bankruptcy or waiting for them to turn to collections and then fight those. You should also work with your insurance. How much is your deductible? If your deductible is so high that it exceeds the several thousands bill you got - do you have a HSA? FSA? These will allow you paying the bill with pre-tax money, saving quite a lot (depending on your brackets and how much you put there). I would expect the insurance to bill you for the deductible, and cover all the rest. Is it not what is happening?