Historic prices for currencies, commodities,
My guess it's a legal agreement between Yahoo and data provider on what data can be stored, displayed and for how long. Check out this list of data providers
"You say you want a more ""stable"" system. Recall from your introductory economics courses that money has three roles: a medium of exchange (here is $, give me goods), a unit of account (you owe me $; the business made $ last year), and a store of value (I have saved $ for the future!). I assume that you are mostly concerned with the store-of-value role being eroded due to inflation. But first consider that most people still want regular currency, so as a medium of exchange or accounting unit anything would face an uphill battle. If you discard that role for your currency, and only want to store value with it, you could just buy equities and commodities and baskets of currencies and debt in a brokerage account (possibly using mutual funds) to store your value. Trillions of dollars' worth of business takes place this way every year already. Virtual currency was a bit of a dot-com bubble thing. The systems which didn't go completely bust and are still around have been beset by money-laundering, and otherwise remain largely an ignored niche. An online fiat currency has the same basic problem that another currency has. You need to trust the central bank not to create more money and cause inflation (or even just abscond with the funds... or go bankrupt / get sued). Perhaps the Federal Reserve may be jerking us around on that front right now.... they're still a lot more believable than a small private institution. Some banks might possibly be trustworthy enough to launch a currency, but it's hard to see why they'd bother (it can't be a big profit center, because people aren't willing to pay too much to just use money.) And an online currency that's backed by commodities (e.g. gold) is going to be subject to potentially violent swings in the prices of commodities. Imagine getting a loan out for your house, denominated in terms of e-gold, and then the price of gold triples. Ouch?" you dont understand the way markets work if you think that. speculators exist in every market. there are FX speculators, does that mean that the the US dollar, yuan, or yen is a game of musical chairs? If an asset or commodity has a use for everyday people, then they are going to buy that asset or commodity. Speculators or traders bring liquidity and reduce volatility to make the price less volatile so everyday people will be able to use it. Bitcoin is a new technology and people are trying to figure out what its value should be. This is r/finance and I have to explain this? Obviously there are many people out there who find value in a decentralized digital currency. they did crash because supply caught up to demand.  &gt; because the only reason people were buying them is because they would go up in value  that is the explanation for why price shot up so quick.  &gt; Sounds exactly like Bitcoin in my opinion  There's genuine utility in cryptocurrency.  Bitcoin is the anchor to all of them.  Btw, there is significant cost to mining bitcoin  &gt; How many people do you know using Bitcoin as a currency?  You can pay bills with it.  A lot better than gold in that regard.  &gt;  It isn't backed by a government or military  historically always a terrible thing for every currency.  The freedom from political whim based valuation is a plus.  &gt; When it crashes and criminals are the only ones using it, then what is it worth?  Criminals would be better off using cash or Monero (a crypto with better privacy safeguards).  But criminal can be a bit subjective.  Bitcoin for instance is the best vehicle for transporting money protecting from thieves whether or not they are government employees.  &gt;  Maybe $100 a coin? $10? Who knows, it sure as hell isn't $5,000 a coin though.  I think we'll see $5000 again, before $3000 or $1000. These markets are independent, just like any other stock market. For example, there are stocks on the Milan stock exchange that are also on the New York stock exchange and have different historical prices. Remember, this is all about offer and demand. The Hong Kong stock exchange has the Hong Kong Dollar as its currency, which is anchored to the USD. Also, there is more trade going on, on the Hong Kong stock exchange. As for the answer, I don't know whether these stocks are exactly the same. I guess they should be, but maybe somebody else could answer that. Interactive Brokers provides historical intraday data including Bid, Ask, Last Trade and Volume for the majority of stocks. You can chart the data, download it to Excel or use it in your own application through their API.  EDIT: Compared to other solutions (like FreeStockCharts.com for instance), Interactive Brokers provides not only historic intraday LAST**** trades **but also historic BID and ASK data, which is very useful information if you want to design your own trading system.  I have enclosed a screenshot to the chart parameter window and a link to the API description. "It's very hard to measure the worth of an abstract concept like money, particularly over long periods of time. In the modern era we have things like the Consumer Price Index (CPI) in the United States, where the Bureau of Labor Statistics literally sends ""shoppers"" out to find prices of things and surveys people to find out what they buy. This results in a variety of ""indexes"" which variously get reported by media outlets as ""inflation"" (or ""deflation"" if the change in value goes the other way). There are also other measurements available like the MIT Billion Prices Project which attempt to make their own reading of the ""worth"" of currencies. Those kinds of things are about the only ways to measure a currency's change in ""value to itself"" because a currency is basically only worth what one can buy with it. While it isn't ""all the world's currencies combined"", there is a concept of the International Monetary Fund's ""Special Drawing Rights (SDR)"", which is a basket of five currencies used by world central banks to help ""back"" each other's currencies, and is (very) occasionally used as a unit of currency for international contracts. One might be able to compare the price of one currency to that of the SDR, or even to any other weighted average of world currencies that one wanted, but I don't think it's done nearly as often as comparing currencies to the basket of goods one can buy to find ""inflation"". Even though one might think what would be important to measure would be overall Money Supply Inflation, much more often people care more about measuring Price Inflation. (Occasionally people worry about Wage Inflation, but generally that's considered a result of high Price Inflation.) In order to try to keep this on topic as a ""personal finance"" thing rather than an ""economics"" thing, I guess the question is: Why do you want to know? If you have some assets in a particular currency, you probably care most about what you'll be able to buy with them in the future when you want or need to spend them. In that sense, it's inflation that you're likely caring about the most. If you're trying to figure out which currency to keep your assets in, it largely depends on what currency your future expenses are likely to be in, though I can imagine that one might want to move out of a particular currency if there's a lot of political instability that you're expecting to lead to high inflation in a currency for a time." The answer is actually very simple: the cost of data. Seriously. Call the CBOE tomorrow and ask yourself. They have two big programs:  1) the penny pilot program, where options trade at penny increments instead of 5 cent increments. This is only extended to a select few symbols because of the amount of data this can generate is too much for the data vendors. Data vendors store and sell historical data. The exchanges themselves often have a big data vending business too. 2) the weekly options program, where only select symbols get these chains because of the amount of data they will generate. Liquidity and demand are factors in determining if the CBOE will consider enabling those series on new issues. (although they have to give the list of which symbols are on these programs to the SEC) What really matters is of course how it compares to future prices. Are we making the assumption that the future prices will be more like the average over the last 100 years (which, by looking at your diagram, we seem to be one standard deviation or so above)?