Stock spread: wide vs. narrow?
The point is that the bid and ask prices dictate what you can buy and sell at (at market, at least), and the difference between the two, or spread, contributes implicitly to your gains or losses. For example, say your $1 stock actually had a bid of $0.90 and an ask of $1.10; i.e. say that $1 was the last price. You would have to buy the stock at the ask price of $1.10, but now you can only sell that stock at the bid price of $0.90. Thus, you would need to make at least that $0.20 spread before you can make a profit.
"All of these frameworks, Markowitz, Mean/CVaR, CARA, etc  sit inside a more general framework which is that ""returns are good"" and ""risk/lack of certainty in the returns is bad"", and there's a tradeoff between the two encoded as some kind of risk aversion number.  You can measure ""lack of certainty in returns"" by vol, CVaR, weighted sum of higher moments, but even sector/region concentration.  Similarly do I want more ""returns"" or ""log returns"" or ""sqrt returns"" in the context of this tradeoff?  You don't need any formal notion of utility at that point - and I don't know what formal ideas of utility beyond ""I want more returns and less risk"" really buys you. The Sharpe ratio only really gets its meaning because you've got some formal asset-pricing notion of utility.   In my view the moment that you're putting constraints on the portfolio (e.g. long only, max weights, don't deviate too much from the benchmark ...) - really you're operating in this more general framework anyway and you're not in ""utility-land"" anymore." Don't know the name but it means you're long with conviction :P  Unlimited gains, maximum loss of 95$  + (8-6) = 97$.  Basically You are long @ 107  - -2 from 105 to 95.  You would have to be ULTRA bullish to initiate this strategy. A bullish (or 'long') call spread is actually two separate option trades.  The A/B notation is, respectively, the strike price of each trade. The first 'leg' of the strategy, corresponding to B, is the sale of a call option at a strike price of B (in this case $165).  The proceeds from this sale, after transaction costs, are generally used to offset the cost of the second 'leg'. The second 'leg' of the strategy, corresponding to A, is the purchase of a call option at a strike price of A (in this case $145). Now, the important part: the payoff.  You can visualize it as so. This is where it gets a teeny bit math-y.  Below, P is the profit of the strategy, K1 is the strike price of the long call, K2 is the strike price of the short call, T1 is the premium paid for the long call option at the time of purchase, T2 is the premium received for the short call at the time of sale, and S is the current price of the stock.  For simplicity's sake, we will assume that your position quantity is a single option contract and transaction costs are zero (which they are not). P = (T2 - max(0, S - K2)) + (max(0, S - K1) - T1) Concretely, let's plug in the strikes of the strategy Nathan proposes, and current prices (which I pulled from the screen).  You have: P = (1.85 - max(0, 142.50 - 165)) - (max(0, 142.50 - 145)) = -$7.80 If the stock goes to $150, the payoff is -$2.80, which isn't quite break even -- but it may have been at the time he was speaking on TV. If the stock goes to $165, the payoff is $12.20. Please do not neglect the cost of the trades!  Trading options can be pretty expensive depending on the broker.  Had I done this trade (quantity 1) at many popular brokers, I still would've been net negative PnL even if NFLX went to >= $165. Yeah, too subjective of a question I shorted BP last year during the deep water crisis, using a leveraged account 20 times larger than the amount of cash I actually had, instantly profitable. I was long Freddie Mac in March 2009 and that took several months to turn to move and turned a 100% gain I've flipped penny stocks trading at .0001 cents, bought a few million shares and sold them at .0002 cents. Sometimes instantly, sometimes over several months because they were illiquid I'm primarily a derivatives trader right now, which I did not know about or understand less than a year ago. Dont have crazy targets, that how you will blow up your account. Have meticulously calculated plans. Also you need to determine what kind of trader you are. "You cannot determine this solely by the ticker length. However, there are some conventions that may help steer you there. Nasdaq has 2-4 base letters BATS has 4 base letters NYSE equity securities have 1-4 base letters. NYSE Mkt (formerly Amex) have 1-4 base letters. NYSE Arca has 4 base letters OTC has 4 base letters. Security types other than equities may have additional letters added, and each exchange (and data vendors) have different conventions for how this is handled. So if you see ""T"" for a US-listed security it would be only be either NASDAQ, NYSE or NYSE Mkt. If you see ""ANET"" then you cannot tell which exchange it is listed on.  (In this case, ANET Arista Networks is actually a NYSE stock). For some non-equity security types, such as hybrids, and debt instruments, some exchanges add ""P"" to the end for ""preferreds"" (Nasdaq and OTC) and NYSE/NYSE Mkt have a variety of methods (including not adding anything) to the ticker.  Examples include NYSE:TFG, NYSEMkt:IPB, Nasdaaq: AGNCP, Nasdaq:OXLCN.  It all becomes rather confusing given the changes in conventions over the years. Essentially, you require data that provides you with ticker, listing location and security type. The exchanges allocate security tickers in conjunction with the SEC so there are no overlaps.  eg. The same ticker cannot represent two different securities. However, tickers can be re-used.  For example, the ticker AB has been used by the following companies:" The best ask is the lowest ask, and the best bid is the highest bid.  If the ask was lower than the bid then they crossed, and that would be a crossed market and quickly resolved. So the bid will almost always be cheaper than the ask. A heuristic is that a bid is the revenue of the stock at any given time while the ask is the cost, so the market will only ever offer a profit to itself not to the liquidity seeker. If examining the book vertically, all orders are usually sorted descending. Since the best ask is the lowest ask, it is on the bottom of the asks, and vice versa for the best bid. The best bid & best ask will be those closest since that's the narrowest spread and price-time priority will promise that a bid that crosses the asks will hit the lowest ask, the best possible price for the bidder and vice versa for an ask that crosses the best bid. Essentially, yes, Peter Lynch is talking about the PEG Ratio. The Price/Earnings to Growth (PEG) Ratio is where you take the p/e ratio and then divide that by the growth rate (which should include any dividends).  A lower number indicates that the stock is undervalued, and could be a good buy. Lynch's metric is the inverse of that: Growth rate divided by the p/e ratio.  It is the same idea, but in this case, a higher number indicates a good value for buying. In either case, the idea behind this ratio is that a fairly priced stock will have the p/e ratio equal the growth rate.  When your growth rate is larger than your p/e ratio, you are theoretically looking at an undervalued stock. "From my recollection of Warren Buffett's book ""Warren Buffett and the Art of Arbitrage"", the following factors determine the difference between the market price of a stock and the future expected price of an acquisition or merger: Time: Assuming the deal will close, the market price should approach the offer price as the closing date approaches. The fact that there is a 14% spread partially reflects the time value of money. Probability: Things could happen between now and closing date which could derail the deal. The higher the spread the more likely the market thinks the deal will not occur. For example, LO shareholders could reject the offer saying it is too low, or anti-trust regulators could say the deal is anti-competitive. Part of this 14% spread indicates the probability of the deal completing." "I would have to disagree with the other responders. In technical analysis of stock charts, various short and long term moving averages are used to give an indication of the trend of the stock in the short and long term, as compared to the current price. I would prefer to use the term moving average (MA) rather than average as the MA is recalculated every day (or at appropriate frequencies for your data) on the period you are using. I would also expand on the term ""moving average"". There are two that are commonly used Going back to the question, of the value of this number, For example if the current price is above the 200 day EWMA and also above the 30 day EWMA, then the stock is broadly trending upwards. Conversely if current price is below the 200 day EWMA and also below the 30 day EWMA, then the stock is broadly trending downwards. These numbers are chosen on the basis of the market you are trading in, the volatility and other factors. For another example of how a number of moving averages are used together, please have a read of Daryl Guppy's Multiple Moving Average, though this does not use moving averages as large as 200 days." "For a retail investor who isn't a Physics or Math major, the ""Beta"" of the stock is probably the best way to quantify risk.  Examples: A Beta of 1 means that a stock moves in line with the market. Over 1 means that you would expect the stock to move up or down faster than the market as a whole. Under 1 means that you would expect the stock to move slower than the market as a whole." Shorts are difficult because you have to find someone to lend the stock to you. In contrast, put options don't require that. They also have some nice properties like you're only out the contract price. The options chain for BSFT will give you an idea of where the market is.  Keep in mind that BSFT only IPO'd last year and announced blowout earnings recently. Make sure the P:E you're looking at is using recent earnings reports! Lets pretend that TELSA decided to split its stock 10 shares for 1. Now the stock is $35 dollars- would that make you happy?  You dont have any idea how companies are valued.   Berkshire Hathaway Inc. Class A NYSE: BRK.A - Oct 31, 12:58 PM EDT 280,210.00 USD Graphs are nothing but a representation of data. Every time a trade is made, a point is plotted on the graph. After points are plotted, they are joined in order to represent the data in a graphical format.  Think about it this way.  1.) Walmart shuts at 12 AM. 2.)Walmart is selling almonds at $10 a pound.  3.) Walmart says that the price is going to reduce to $9 effective tomorrow. 4.) You are inside the store buying almonds at 11:59 PM.  5.) Till you make your way up to the counter, it is already 12:01 AM, so the store is technically shut. 6.) However, they allow you to purchase the almonds since you were already in there.  7.) You purchase the almonds at $9 since the day has changed. 8.) So you have made a trade and it will reflect as a point on the graph. 9.) When those points are joined, the curves on the graph will be created. 10.) The data source is Walmart's system as it reflects the sale to you. ( In your case the NYSE exchange records this trade made). Buying a stock is just like buying almonds. There has to be a buyer. There has to be a seller. There has to be a price to which both agree. As soon as all these conditions are met, and the trade is made, it is reflected on the graph. The only difference between the graphs from 9 AM-4 PM, and 4 PM-9 AM is the time. The trade has happened regardless and NYSE(Or any other stock exchange) has recorded it! The graph is just made from that data. Cheers. There are about 250 trading days in a year. There are also about 1,900 stocks listed on the NYSE.  What you're asking for would require about 6.2M rows of data. Depending on the number of attributes you're likely looking at a couple GB of data.  You're only getting that much information through an API or an FTP. the difference would be taxes...  Lets say you have two lots, one with a 10 dollar gain, and one with a 20 dollar gain.  And lets say you decide to sell one lot this year, and the other lot in 10 years.  AND, lets say that it turns out the stock price is exactly the same in ten years as it is when you sell the first lot. In all likelyhood, you'll have more income, and therefore you are likely to be in a different marginal tax rate.  If you believe that you're more likely to pay more taxes in 10 years, then sell the lot with the higher gain now.  If you believe you're more likely to pay more taxes now, then sell the lot with the lower gain now.