What is meant by “buy-side firm” and “sell-side firm”?
Traditionally, dealers and broker-dealers were in contact with the actual producers of a product or issuers of a security, selling it at the exchange on their behalf.  Consumers would traditionally be on the buy side, of course. These days, anyone can enter the market on either side.  Even if you don't hold the security or product, you could sell it, and take on the risk of having to stock up on it by the delivery date in exchange for cash or other securities.  On the other side, if you can't hold the product or security you could still buy it, taking on the risk of having to dispose of it somehow by delivery in exchange for cash or other securities. In either case you (the sell-side) take on risk and provide products/securities/cash.  This is most commonly known as market making.  Modern literature coins the terms liquidity taker (buy-side) and liquidity provider (sell-side).  Even more accurately, risk management literature would use the terms risk-taker (sell-side) and risk spreader or risk reducer (buy side). This is quite illustrative in modern abstract markets.  Take a market that allows for no offsetting or hedging because the product in question is abstract or theoretical, e.g. weather trading, volatility trading, inflation trading, etc.  There's always one party trying to eliminate dependence on or correlation to the product (the risk reducer, buy-side) and the counterparty taking on their risk (sell-side).
This thread has been linked to from elsewhere on reddit.    - [/r/BusinessHub] [Honest day-in-the-life of a sell-side trader. Also AMA. • /r/finance](http://np.reddit.com/r/BusinessHub/comments/2cfc6s/honest_dayinthelife_of_a_sellside_trader_also_ama/)   *^If ^you ^follow ^any ^of ^the ^above ^links, ^respect ^the ^rules ^of ^reddit ^and ^don't ^vote ^or ^comment. ^Questions? ^Abuse? [^Message ^me ^here.](http://www.reddit.com/message/compose?to=%2Fr%2Fmeta_bot_mailbag)* You're buying the operations of firm A for $450, or 4.5x EBITDA. You're buying the operations of firm B for $500, or 5.0x EBITDA.  You're paying a higher multiple for firm B.  Of couse subtracting cash 'skews multiples' - but you need to pull it out. You're paying for a business' ability generate that EBITDA over time. Cash is a one-shot deal. You need to pull it out to get the value of what you're actually investing in. "Cart's answer describes well one aspects of puts: protective puts; which means using puts as insurance against a decline in the price of shares that you own.  That's a popular use of puts.  But I think the wording of your question is angling for another strategy: Writing puts. Consider: Cart's strategy refers to the buyer of a put.  But, on the transaction's other side is a seller of the put – and ultimately somebody created or wrote that put contract in the first place!  That first seller of the put – that is, the seller that isn't just selling one they themselves bought – is the put writer. When you write a put, you are taking on the obligation to buy the other side's stock at the put exercise price if the stock price falls below that exercise price by the expiry date.  For taking on the obligation, you receive a premium, like how an insurance company charges a premium to insure against a loss. Example:  Imagine ABC Co. stock is trading at $25.00.  You write a put contract agreeing to buy 100 shares of ABC at $20.00 per share (the exercise price) by a given expiration date.  Say you receive $2.00/share premium from the put buyer.  You now have the obligation to purchase the shares from the put buyer in the event they are below $20.00 per share when the option expires – or, technically any time before then, if the buyer chooses to exercise the option early. Assuming no early assignment, one of two things will happen at the option expiration date: ABC trades at or above $20.00 per share. In this case, the put option will expire worthless in the hands of the put buyer.  You will have pocketed the $200 and be absolved from your obligation.  This case, where ABC trades above the exercise price, is the maximum profit potential. ABC trades below $20.00 per share.  In this case, the put option will be assigned and you'll need to fork over $2000 to the put buyer in exchange for his 100 ABC shares.  If those shares are worth less than $18.00 in the market, then you've suffered a loss to the extent they are below that price (times 100), because remember – you pocketed $200 premium in the first place.  If the shares are between $18.00 to $20.00, you're still profitable, but not to the full extent of the premium received. You can see that by having written a put it's possible to acquire ABC stock at a price lower than the market price – because you received some premium in the process of writing your put.  If you don't ""succeed"" in acquiring shares on your first write (because the shares didn't get below the exercise price), you can continue to write puts and collect premium until you do get assigned. I have read the book ""Money for Nothing (And Your Stocks for FREE!)"" by Canadian author Derek Foster.  Despite the flashy title, the book essentially describes Derek's strategy for writing puts against dividend-paying value stocks he would love to own.  Derek picks quality companies that pay a dividend, and uses put writing to get in at lower-than-market prices.  Four Pillars reviewed the book and interviewed Derek Foster: Money for Nothing: Book Review and Interview with Derek Foster. Writing puts entails risk.  If the stock price drops to zero then you'll end up paying the put exercise price to acquire worthless shares!  So your down-side can easily be multiples of the premium collected.  Don't do this until and unless you understand exactly how this works.  It's advanced. Note also that your broker isn't likely to permit you to write puts without having sufficient cash or margin in your account to cover the case where you are forced to buy the stock.  You're better off having cash to secure your put buys, otherwise you may be forced into leverage (borrowing) when assigned.  Additional Resources: The Montreal Exchange options guide (PDF) that Cart already linked to is an excellent free resource for learning about options.  Refer to page 39, ""Writing secured put options"", for the strategy above. Other major options exchanges and organizations also provide high-quality free learning material:" "As Dheer pointed out, Wikipedia has a good definition of what a negotiable instrument is.  A security is an instrument or certificate that signifies an ownership interest in something tangible. 1 share of IBM represents some small fraction of a company. You always have the ability to choose a price you are willing to pay -- which may or may not be the price that you get. A derivative is a level of abstraction linked by a contract to a security... if you purchase a ""Put"" contract on IBM stock, you have a contractural right to sell IBM shares at a specific price on a specific date. When you ""own"" a derivative, you own a contract -- not the actual security." I was merely trying to be helpful - Conceptually, you have dump this idea that something is skewed. It isn't. Firm A sold for $500 (equity value aka purchase price to shareholders) + debt (zero) - cash (50) for 450.  Enterprise value is the cash free, debt free sale price.  The implied ev multiple is 4.5x on A - that is the answer. The other business sold for a higher multiple of 5x.  If you would pile on more cash onto A, the purchase price would increase, but the EV wouldn't.      The idea is to think hard about the difference between equity value and enterprise value when examining a transaction. You kind of have to take what the market is offering.  The easiest way would be for you to have a system by which you could purchase the entire business and then dispose of the FFE and other liabilities as part of the sale.  Then you could pick and choose which of the clients you want to add to your portfolio of clients and those you would release back to the market.  The valuation of the transaction is the trick.  Taking the new client and managing it profitably is presumably something you feel you are well-suited to do already. "The two dimensions are to open the trade (creating a position) and to buy or sell (becoming long or short the option). If you already own an option, you bought it to open and then you would sell it to close. If you don't own an option, you can either buy it to open, or sell it (short it) to open. If you are already short an option, you can buy it back to close. If you sell to open covered, the point is you're creating a ""covered call"" which means you own the stock, and then sell a call. Since you own the stock, the covered call has a lot of the risk of loss removed, though it also subtracts much of the reward possible from your stock." "I can see two possibilities. Either a deal is struck that someone (the company itself, or a large owner) buys out the remaining shares. This is the scenario @mbhunter is talking about, so I won't go too deeply into it, but it simply means that you get money in your bank account for the shares in question the same as if you were to sell them for that price (in turn possibly triggering tax effects, etc.). I imagine that this is by far the most common approach. The other possibility is that the stock is simply de-listed from a public stock exchange, and not re-listed elsewhere. In this case, you will still have the stock, and it will represent the same thing (a portion of the company), but you will lose out on most of the ""market"" part of ""stock market"". That is, the shares will still represent a monetary value, you will have the same right to a portion of the company's profits as you do now, etc., but you will not have the benefit of the market setting a price per share so current valuation will be harder. Should you wish to buy or sell stock, you will have to find someone yourself who is interested in striking a deal with you at a price point that you feel comfortable with." Buy and hold doesn't have an exact definition, as far as I know.  In my opinion, it's offered as a contrast to those who trade too frequently, or panic every time the market drops 2%.  For the general market, e.g. your S&P index holdings. You sell to rebalance to your desired asset allocation. As a personal example, at 50, I was full up invested, 95%+ in stocks. When my wife and I were retired (i.e. let go from company, but with no need to go back to work) I started shifting to get to a more sane allocation, 80/20. The ideal mix may be closer to 60/40.  Also, there are times the market as a whole is overvalued as measure by P/E and/or CAPE, made popular by Nobel Prize winning Robert Shiller. During these times, an allocation shift might make sense.  For the individual stocks, you had best have a strategy when you buy. Why did you buy XYZ? Because they had promise, decent company with a good outlook for their product? Now that they are up 300%, can they keep gaining share or expand their market? Sometimes you can keep raising the bar, and keep a company long term, really long. Other times, the reason you bought no longer applies, they are at or above the valuation you hoped to achieve.  Note - I noticed from another question, the OP is in the UK. I answer this my from US centric view, but it should still apply to OP in general. The question was not tagged UK when I replied. 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. Book value = sell all assets and liquidate company . Then it's the value of company on book. Price = the value at which it's share gets bought or sold between investors.  If price to book value is less than one, it shows that an 100$ book value company is being traded at 99$ or below. At cheaper than actually theoretical price. Now say a company has a production plant . Situated at the most costliest real estate . Yet the company's valuation is based upon what it produces, how much orders it has etc while real estate value upon which plant is built stays in book while real investors don't take that into account (to an extend). A construction company might own a huge real estate inventory. However it might not be having enough cash flow to sustain monthly expense. In this scenario , for survival,i the company might have to sell its real estate at discount. And market investors are fox who  could smell trouble and bring price way below the book value  Hope it helps "Selling short is simply by definition the selling, then later re-buying of stock you don't initially own. Say you tally your entire portfolio balance: the quantity of each stock you own, and your cash assets. Let's call this your ""initial position"". We define ""profit"" as any increase in assets, relative to this initial position. If you know a particular stock will go down, you can realize a profit by selling some of that stock, waiting for the price to go down, then buying it back. In the end you will have returned to your initial position, except you will have more cash. If you sell 10 shares of a stock valued at £1.50, then buy them back at £1.00, you will make a £5.00 profit while having otherwise returned to your previous position. If you do the same, but you initially owned 1000 shares, sold just 10 of those, then bought 10 back, that's still a profit of £5.00. Selling short is doing the same thing, but with an initial and ending balance of 0 shares. If you initially own 0 shares, sell 10, then buy 10 back, you return to your initial position (0 shares) plus a profit of £5.00. (And in practice you must also pay a borrowing fee to do this.) The advantage of selling short is it can be done with any stock, not just those currently owned." This has never really adequately explained it for me, and I've tried reading up on it all over the place. For a long time I thought that in a trade, the market maker pockets the spread *for that trade*, but that's not the case.  The only sensible explanation I've found (which I'm not going to give in full...) is that the market maker will provide liquidity by buying and selling trades they have no actual view on (short or long), and if the spread is higher, that contributes directly to the amount they make over time when they open and close positions they've made.  It would be great to see a single definitive example somewhere that shows how a market maker makes money. For the lenders to sell their positions they need buyers on the other side. For a large brokerage that means they should always be able to find another lender. For many contracts the client may have no idea they are a lender as lending is part of their agreement with the broker For every seller, there's a buyer. Buyers may have any reason for wanting to buy (bargain shopping, foolish belief in a crazy business, etc).  The party (brokerage, market maker, individual) owning the stock at the time the company goes out of business is the loser . But in a general panic, not every company is going to go out of business. So the party owning those stocks can expect to recover some, or all, of the value at some point in the future. Brokerages all reserve the right to limit margin trading (required for short selling), and during a panic would likely not allow you to short a stock they feel is a high risk for them.