Looking for a stock market simulation that's as close to the real thing as possible
"There is a site that treats you like a fund manager in the real market, Marketoracy, http://marketocracy.com/. Each user is given 1 million in cash. You can have multiple ""mutual funds"", and the site allows use to choose between two types of strategies, buy/sell, short/cover. Currently, options are not supported. The real value of the site is that users are ranked against each other (of course, you can op out of the rankings). This is really cool because you can determine the real worth of your returns compared to the rest of investors across the site. A couple years back, the top 100 investors were invited to come on as real mutual fund managers - so the competition is legitimate. Take a look at the site, it's definitely worth a try. Were there other great sites you looked at?" "Thinkorswim's ThinkDesktop platform allows you to replay a previous market day if you wish. You can also use paper money in stocks, options, futures, futures options, forex, etc there. I really can't think of any other platform that allows you to dabble around in so many products fictionally. And honestly, if all that ""make[s] the learning experience a bit more complicated"" and demotivates you, well thats probably a good thing for your sake." "Many online brokers have a ""virtual"" or ""paper"" trading feature to them.  You can make trades in near-real time with a fake account balance and it will treat it as though you were making the trade at that time.  No need to manage the math yourself - plus, you can even do more complicated trades (One-Cancels-Other/One-Triggers-Other)." Stock market is like poker: you don't take the same risks when it is fake money and thus you don't learn the same lessons from your mistakes. I would recommend instead to play with real market and real money (rule #0: use only money that you don't need). Start with safe products and go to the bath progressively. It took me about ten years and I am still learning. I have a free account on http://optionshouse.com/ that allows me to invest fake money into different stocks and test their tracking software. It is free and easy to do, just create an account there and they give you $4000 (fake) to invest in the stock market. They do this so that you can test their tracking and other assorted tools, in hopes that you'll choose to invest your real hard earned money with them.
"The answer to your question depends very much on your definition of ""long-term"". Because let's make something clear: an investment horizon of three to six months is not long term. And you need to consider the length of time from when an ""emergency"" develops until you will need to tap into the money. Emergencies almost by definition are unplanned. When talking about investment risk, the real word that should be used is volatility. Stocks aren't inherently riskier than bonds issued by the same company. They are likely to be a more volatile instrument, however. This means that while stocks can easily gain 15-20 percent or more in a year if you are lucky (as a holder), they can also easily lose just as much (which is good if you are looking to buy, unless the loss is precipitated by significantly weaker fundamentals such as earning lookout). Most of the time stocks rebound and regain lost valuation, but this can take some time. If you have to sell during that period, then you lose money. The purpose of an emergency fund is generally to be liquid, easily accessible without penalties, stable in value, and provide a cushion against potentially large, unplanned expenses. If you live on your own, have good insurance, rent your home, don't have any major household (or other) items that might break and require immediate replacement or repair, then just looking at your emergency fund in terms of months of normal outlay makes sense. If you own your home, have dependents, lack insurance and have major possessions which you need, then you need to factor those risks into deciding how large an emergency fund you might need, and perhaps consider not just normal outlays but also some exceptional situations. What if the refrigerator and water heater breaks down at the same time that something breaks a few windows, for example? What if you also need to make an emergency trip near the same time because a relative becomes seriously ill? Notice that the purpose of the emergency fund is specifically not to generate significant interest or dividend income. Since it needs to be stable in value (not depreciate) and liquid, an emergency fund will tend towards lower-risk and thus lower-yield investments, the extreme being cash or the for many more practical option of a savings account. Account forms geared toward retirement savings tend to not be particularly liquid. Sure, you can usually swap out one investment vehicle for another, but you can't easily withdraw your money without significant penalties if at all. Bonds are generally more stable in value than stocks, which is a good thing for a longer-term portion of an emergency fund. Just make sure that you are able to withdraw the money with short notice without significant penalties, and pick bonds issued by stable companies (or a fund of investment-grade bonds). However, in the present investment climate, this means that you are looking at returns not significantly better than those of a high-yield savings account while taking on a certain amount of additional risk. Bonds today can easily have a place if you have to pick some form of investment vehicle, but if you have the option of keeping the cash in a high-yield savings account, that might actually be a better option. Any stock market investments should be seen as investments rather than a safety net. Hopefully they will grow over time, but it is perfectly possible that they will lose value. If what triggers your financial emergency is anything more than local, it is certainly possible to have that same trigger cause a decline in the stock market. Money that you need for regular expenses, even unplanned ones, should not be in investments. Thus, you first decide how large an emergency fund you need based on your particular situation. Then, you build up that amount of money in a savings vehicle rather than an investment vehicle. Once you have the emergency fund in savings, then by all means continue to put the same amount of money into investments instead. Just make sure to, if you tap into the emergency fund, replenish it as quickly as possible." I suppose it depends on what you mean by replicate.  I don't take his meaning as to be able to create a brain with real neurons and such (this is actually possible*).  I take it to mean replicate the functionality of the brain as closely as possible.  I've been tracking the progress of the Blue Brain project which is attempting to do just this via software abstraction and simulation.  It's a lofty goal.  I like lofty goals.  I think they often accomplish more faster.  But having said that, I think trying to do this with hardware without the abstraction is even more difficult because as you say, we don't completely understand how the brain works.  It's much easier to write or adjust simulation code than it is to redo hardware.  Of course, the simulation route is less efficient but it's more flexible as new theories and information are generated, you just revise the simulation software.  *Have a baby or do something like this: http://www.physorg.com/news/2011-12-bioelectric-tadpoles-eyes-tail.html  edit: would someone mind replying instead of just downvoting? "The basic answer is that you are comparing apples and oranges.  On the one hand, you are considering a case where someone buys a single already-built house.  On the other hand, you are considering a case where someone buys a large piece of land, builds 10 houses, and (presumably) sells or rents the 9 they're not living in. Those are two totally different endeavors.  It might be reasonable to compare the cost of a plot of land sized for a single house to the cost of a similar plot with a house already on it.  But you can't directly compare the cost of buying 10 houses worth of land to the cost of one house.  As other answers have mentioned, building 10 houses involves a massive amount of work: an architect has to design a house, somebody has to get permits to build it, someone may have to get water/power/sewage hookups, somebody has to physically build it -- then multiply all that by 10 for 10 houses.  Once you're done, you still haven't recouped your investment.  You just have 10 houses.  Now you have to sell them, which is a whole other job in itself. Because the things you're comparing are so different, the potential buyers for the two cases are also completely different.  This explains the ""inconsistency"" between the asking price and your perception of its value.  The two kinds of properties are in two different markets.  The people looking to buy a single home are just regular people looking for a place to live (or maybe trying to get a rental property).  The people looking to buy a 10-house plot are real estate developers with a whole different set of concerns.  There could be many reasons why the land hasn't been purchased yet, but you can't compare it to the cost of comparable houses, because almost no one who is looking for a house is going to consider buying 2 acres of land instead.  It's like asking why filling up your car with gas is so much more expensive per gallon than buying a gas station and giving yourself free gas.  They're just not the same thing.   But given the size of the land, I can join forces with other people which are also in the market and totally bring down the land price per piece to say 100k? You can do that, but basically what you'll be doing is forming a real estate development company of some sort.  This opens a whole other world of possible snafus (for instance, how ownership is to be divided, and what happens if the owners disagree on appropriate development of their portions). It is absolutely possible to make money by buying land and building houses on it, especially in California.  People do it all the time.  But it's not something you should attempt if you don't know what you're doing, and it's definitely not the same thing as just buying a house to live in." When on this topic, you'll often hear general rules of thumb. And, similar to the 'only buy stocks if you plan to hold more than X years' there are going to be periods where if you buy at a bottom right before the market turns up, you might be ahead just months after you buy. I'd say that if you buy right, below market, you're ahead the day you close.  Edit - I maintain, and have Schiller providing supporting data) that real estate goes up with inflation in the long term, no more, no less. If the rise were perfectly smooth, correlated 100% month to month, you'd find it would take X years to break even to the costs of buying, commission and closing costs. If we call that cost about 8%, and inflation averages 3, it points to a 3 year holding period to break even. But, since real estate rises and falls in the short term, there are periods longer than 4 years where real estate lags, and very short periods where it rises faster than the costs involved.  The buy vs rent is a layer right on top of this. If you happen upon a time when the rental market is tight, you may buy, see the house decline 10% in value, and when the math is done, actually be ahead of the guy that rented. "In addition to what @George Marian said, a very large portion of trades are from computer programs trained to make trades when certain apparent patterns are observed.  Since these programs are not all designed in the same way, much of the supply and demand is a result of different algorithms with different ""opinions"" on what the stock is doing." "Finding the ""optimal"" solution (and even defining what optimal is) would probably take a lot of searching of all the possible combinations of stocks you could buy, given that you can't buy fractional shares. But I'd guess that a simple ""greedy"" algorithm should get you close enough. For any given portfolio state, look at which stock is furthest below the target size - e.g. in your example, S3 is 3.5% away whereas S1 is only 3.1% away and S2 is over-sized. Then decided to buy one stock of S3, recalculate the current proportions, and repeat until you can't buy more stocks because you've invested all the money. If you have to pay a transaction fee for each kind of stock you purchase you might want to calculate this in larger lot sizes or just avoid making really small purchases." "You could use any of various financial APIs (e.g., Yahoo finance) to get prices of some reference stock and bond index funds.  That would be a reasonable approximation to market performance over a given time span. As for inflation data, just googling ""monthly inflation data"" gave me two pages with numbers that seem to agree and go back to 1914.  If you want to double-check their numbers you could go to the source at the BLS. As for whether any existing analysis exists, I'm not sure exactly what you mean.  I don't think you need to do much analysis to show that stock returns are different over different time periods." "You don't need to use a real stock like GLD.  You can just create a ""stock"" called something like ""1 oz Gold"" and buy and sell them as if they were shares.  It won't auto-update the price like GLD, but that's not a big deal to update manually once a month or so. I prefer to have accurate data that is correct at a particular point in time to having data that is 2-3% off, or that requires entering the ounces as 10x reality.  YMMV. This is very similar to how you track US Savings Bonds in Quicken (and might be described in the help under that topic.)"