How's the graph of after/pre markets be drawn?
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. the data source is the same as the live market trading. pre and after market trading are active markets and there are actual buyers and sellers getting their orders matched.
Any person at any time may produce their own currency, one can even do so on the back of a paper napkin, ripped beer coaster or whatever.  This is NOT a banking privilege, it is within the lawful ability of anyone capable of engaging in commerce. It is called a 'negotiable instrument' ... it gives the holder rights to a sum of money.  Notice that I say 'holder' ... this is what distinguishes it from a non-negotiable instrument, the fact that you don't need to redeem it from source, you can pass it to another who then becomes the 'holder in due course' and thus obtains the rights conferred. The conferable rights over a sum of money (or, indeed, other asset) are themselves 'value' Do banks do this ?  Yes, all the time! ... one of the simplest examples are cheques drawn against the bank, which are considered 'as good as cash'.  Usually they will be drawn out to the order of the person you wish to pay ... but can equally be drawn out to bearer.  The only reasons they resist making out to bearer is : But you can write your own at 'any time' on 'any thing' ... See the apocryphal, yet deliciously entertaining, tale of the 'negotiable cow' "This is the best tl;dr I could make, [original](https://www.bloomberg.com/news/articles/2017-06-16/the-housing-recovery-is-leaving-out-most-of-america) reduced by 85%. (I'm a bot) ***** &gt; For further evidence of the uneven recovery among U.S. housing markets, how&amp;#039;s this: In the 10 most expensive U.S. metropolitan areas, median home values have increased by 63 percent since 2000, after adjusting for inflation.  &gt; Home prices in 3 out of 5 metropolitan areas remain below their pre-recession peak, and home prices in low-income neighborhoods are faring even worse.  &gt; Home prices increased in 97 out of the 100 largest metropolitan areas, according to the report.   ***** [**Extended Summary**](http://np.reddit.com/r/autotldr/comments/6hpc6k/the_housing_recovery_is_leaving_out_most_of/) | [FAQ](http://np.reddit.com/r/autotldr/comments/31b9fm/faq_autotldr_bot/ ""Version 1.65, ~146042 tl;drs so far."") | [Feedback](http://np.reddit.com/message/compose?to=%23autotldr ""PM's and comments are monitored, constructive feedback is welcome."") | *Top* *keywords*: **percent**^#1 **home**^#2 **price**^#3 **report**^#4 **housing**^#5" It can be zero or negative given the current market conditions. Any money parked with treasury bonds is 100% risk free. So if I have a large amount of USD, and need a safe place to keep, then in today's environment even the banks (large as well) are at risk. So if I park my money with some large bank and that bank goes bankrupt, my money is gone for good. After a long drawn bankruptcy procedure, I may get back all of it or some of it. Even if the bank does not go bankrupt, it may face liquidity crises and I may not be able to withdraw when I want.  Hence it's safer to keep it in Treasury bonds even though I may not gain any interest, or even lose a small amount of money. At least it will be very safe.   Today there are very few options for large investors (typically governments and institutional investors.) The Euro is facing uncertainty. The Yuan is still regulated. There is not enough gold to buy (or to store it.) Hence this leads towards the USD.  The very fact that USD is safe in today's environment is reflected in the Treasury rates. Your asset mix should reflect your own risk tolerance.  Whatever the ideal answer to your question, it requires you to have good timing, not once, but twice. Let me offer a personal example. In 2007, the S&P hit its short term peak at 1550 or so. As it tanked in the crisis, a coworker shared with me that he went to cash, on the way down, selling out at about 1100. At the bottom, 670 or so, I congratulated his brilliance (sarcasm here) and as it passed 1300 just 2 years later, again mentions how he must be thrilled he doubled his money. He admitted he was still in cash. Done with stocks. So he was worse off than had he held on to his pre-crash assets. For sake of disclosure, my own mix at the time was 100% stock. That's not a recommendation, just a reflection of how my wife and I were invested.  We retired early, and after the 2013 excellent year, moved to a mix closer to 75/25. At any time, a crisis hits, and we have 5-6 years spending money to let the market recover. If a Japanesque long term decline occurs, Social Security kicks in for us in 8 years.  If my intent wasn't 100% clear, I'm suggesting your long term investing should always reflect your own risk tolerance, not some short term gut feel that disaster is around the corner. At my first job (moderate sized quant prop fund) we inexplicably used Macs. Excel on a mac is a nightmare- if you tried to graph more than, say, 2000 data points it would grind to a halt, though this was some time ago. In retrospect maybe they were conditioning us to program rather than use excel... I understand now. Thank you. How important is the existence of effective price discovery tools in a market?   And the example that you gave of a farmer is good, but when I as the owner of a company, get futures regarding, say, the stocks that I own of my company, won't that be insider trading if I do that after knowing that the value of my stocks will fall? If people assume price discovery in this case, won't they also have to assume that I am doing insider trading? "Google Docs spreadsheets have a function for filling in stock and fund prices.  You can use that data to graph (fund1 / fund2) over some time period. Syntax: =GoogleFinance(""symbol"", ""attribute"", ""start_date"", ""num_days|end_date"", ""interval"") where: This analysis won’t include dividends or distributions. Yahoo provides adjusted data, if you want to include that." "Hmm, that doesn't quite answer my question -- sorry if I was unclear. Let me try rephrasing:  Here's what I'm asking: is the Black-Scholes equation derived using martingale pricing methods (e.g. Girsanov's theorem, the Martingale Representation Theorem, and so on) *equivalent* to the equation derived using the method in the 1973 paper, e.g. constructing a risk-less portfolio and eliminating the drift term? I was led to believe that both of these approaches *lead to the same result*.  I agree that there's an enormous difference between ""equilibrium"" and ""arbitrage free"" *term structure models*; I'm just not convinced that this is a meaningful difference in the case where market completeness holds, e.g. European equity options.   As you correctly said, it's generally impossible to parameterise a Vasicek model to get it to match the observed term structure, while this is something that can be readily done with a Hull-White / Ho-Lee / Libor Market Model. Hence, the prices you get from a Vasicek will obviously be different from what you get using a Hull-White (since you won't be able to match the initial term structure). But such a difference doesn't hold with a Black-Scholes equation derived using martingale vs. the original method.  Sorry if this sounds nitpicky; I just want to make sure I'm understanding these concepts correctly.  EDIT: Added italics."