Why have I never seen a stock split?
Are you sure you're not just looking at prices that are adjusted for the split, e.g. Yahoo? For example, Gilead Sciences (GILD) split a few months ago, but if you look at a price chart, there isn't an interruption even though the split is clearly marked. (Look in the past six months; it split in January). However, you could also simply be watching companies that happen to not split, for a variety of reasons. This isn't a criticism, but rather just a consequence of whatever stocks you happen to be watching.  However, a quick search for information on stock splits yields a few articles (mainly from the Motley Fool) that argue that fewer companies are performing stock splits in recent years; the articles mainly talk about tech companies, and they make the argument that even though the shares in Google and Apple have a high stock price: Google and Apple aren't all that expensive by traditional valuation   metrics. Google trades at just 15 times next year's projected   profitability. Apple fetches a mere 13 times fiscal 2012's bottom-line estimates. These articles are a bit dated in terms of the stock prices, but the rationale is probably still good. Similar logic could apply for other companies; for example, since May 2009, Panera's stock price has climbed by almost a factor of 4 without splitting. The articles also make the point that stock splits were traditionally seen as bullish signs because: Companies splitting to bring their share prices back down to more   accessible levels were optimistic in building those sand castles back   up. One could make a fair argument that the overall economic climate isn't as bullish as it used to be, although I would only be convinced that this was affecting stock splits if data could be gathered and tested. A stock split can also raise the price of a stock because if small investors feel the stock is suddenly more accessible to them, they purchase more of it and might therefore drive up the price. (See the Investopedia article on stock splits for more information). Companies might not see the necessity in doing this because their stock price isn't high enough to warrant a split or because the price isn't high enough to outprice smaller investors.  One interesting point to make, however, is that even though stock splits can drive small investors to buy more of the stock, this isn't always a gain for the company because professional investors (firms, institutions, etc.) have a tendency to sell after a split. The paper is a bit old, but it's still a very neat read. It's possible that more and more companies no longer see any advantage to splitting because it might not affect their stock price in the long run, and arguably could even hurt it. Considering that large/professional investors likely hold a higher percentage of a company's shares than smaller investors, if a stock split triggers a wave of selling by the former, the increasing propensity to buy of the latter may not be enough to offset the decline in price.  Note: My answer only refers to standard stock splits; the reasons above may not apply to a decrease in the number of reverse stock splits (which may not be a phenomenon; I don't know). You haven't seen one because you haven't looked for one properly. You can set a google alert for stock split and get information about major issues splitting their stocks quite regularly, as well as a daily dose of recommendations from people without a say in the matter for big companies to split their stock. Stock splits are announced in advance by company management. If you want to see one split, well, a reverse split anyway, keep an eye on TZA, FAZ, BGZ, and any Direxion fund.  These funds decay continuously forever.  Once they get close to $10-$15 or so, they reverse-split them back to the $30-$50 range and the process starts over.  This happens about once a year. A few years ago I sent Direxion an email asking what happens when they run out of shares to reverse split and the reply was that's its an open fund where shares can be created or redeemed at will.  That still didn't answer the question of what happens when they run out of shares.  If they create new shares, the price will drop below the $10 level where many fund managers aren't allowed to buy.
"There's no need for an index to have a currency as its purpose is not to act as an asset but rather to signal investors about the performance of a collection of stocks. An index can be price-weighted, meaning that its value equals the (arithmetic) average of the prices of each stock in the index. With no stock splits, the return on this index is the same as the return on a portfolio composed of one share of each stock. If there is a stock split, however instead of dividing by the number of stocks, as you normally would when taking the arithmetic average, you divide it by the number that will make the value of the index pre-stock-split (arithmetic average) equal to the value post stock split. Then use that dividing number for all periods until a new stock split occurs.  An index can be value-weighted, meaning that its changes in value track the percentage changes in total market capitalization of the stocks in the index. Price weighted indexes ignore for ""firm size"" and percentage changes in price weighted indexes are not robust to stock-splits. Value weighted indexes take ""firm size"" into account and are robust to stock-splits. DJIA is price-weighted. S&P 500 is value-weighted." On Monday, the 27th of June 2011, the XIV ETF underwent a 10:1 share split. The Yahoo Finance data correctly shows the historic price data adjusted for this split.  The Google Finance data does not make the adjustment to the historical data, so it looks like the prices on Google Finance prior to 27 June 2011 are being quoted at 10 times what they should be.   Coincidentally, the underlying VIX index saw a sudden surge on the Friday (24 June) and continued on the Monday (27 June), the date that the split took effect.  This would have magnified the bearish moves seen in the historic price data on the XIV ETF. Here is a link to an article detailing the confusion this particular share split caused amongst investors.  It appears that Google Finance was not the only one to bugger it up.  Some brokers failed to adjust their data causing a lots of confusion amongst clients with XIV holdings at the time. This is a recurring problem on Google Finance, where the historic price data often (though not always) fails to account for share splits. I'm going to guess that you found this because of a stock screener.  This company went through a 1:20 reverse split on June 30, so every 20 shares outstanding became a single share.  Where before you had 20 shares worth $100 you now have 1 share worth $100, the value of the company doesn't change because of a split.  This company was never trading for $30+ per share.  Reverse splits are typical of a floundering company trading on an exchange that has a minimum share price requirement.  While reverse splits don't change the value of the company, just the number of shares outstanding and the price per share, no healthy company performs a reverse split.  Reverse splits are generally a massive signal to jump ship... The company seems to be trading for $1 right now, why the value fell from a pre-split $1.65 ($33/20) to $1 is anyone's guess; how the company ever got to $1.65 is also anyone's guess. But looking at the most recent 10-Q there are numerous causes for concern:  Note 2. Capital Stock On March 6, 2017, the Company issued as compensation for services provided a total of 650,000 common shares with a fair value of $390,000 to a third party. The fair value of the shares was based on the price quoted on the OTC pink sheets on the grant date. this indicates a share price of $0.60 ($390,000/650,000) as of 3/6/2017, just to reinforce that the google price chart doesn't show the true past but a past adjusted for the split Results of Operations The three months ended March 31, 2017 compared to the three months ended March 31, 2016 For the three months ended March 31, 2017 compared to the three months ended March 31, 2016, total revenues were $0 and $0, respectively, and net losses from operations were $414,663 and $26,260, respectively. The net losses were attributable to costs attributable to operating as a public company, in particular, common stock with a valuation of $390,000 that was issued to an investor relations firm in the first quarter of 2017. Going Concern As of March 31, 2017, there is substantial doubt regarding our ability to continue as a going concern as we have not generated sufficient cash flow to fund our proposed business. We have suffered recurring losses from operations since our inception. In addition, we have yet to generate an internal cash flow from our business operations or successfully raised the financing required to develop our proposed business. As a result of these and other factors, our independent auditor has expressed substantial doubt about our ability to continue as a going concern.    Liquidity and Capital Resources We had no cash as of the date of March 31, 2017. Additionally, since there is no balance sheet in the last 10-Q (another bad sign), the last annual report 10-K has this balance sheet: So the company: So why did the stock value plummet? It's anyones' guess but there is no shortage of ways to justify it.   In fact, it's reasonable to ask how is this company still worth $3mm ($1 * 3mm shares outstanding)... "There is one other factor that I haven't seen mentioned here.  It's easy to assume that if you buy a stock, then someone else (another stock owner) must have sold it to you.  This is not true however, because there are people called ""market makers"" whose basic job is to always be available to buy shares from those who wish to sell, and sell shares to those who wish to buy.  They could be selling you shares they just bought from someone else, but they also could simply be issuing shares from the company itself, that have never been bought before. This is a super oversimplified explanation, but hopefully it illustrates my point." "I am strongly skeptical of this.  In fact, after reading your question, I did the following: I wrote a little program in python that ""simulates"" a stock by flipping a coin. Each time the coin comes up heads, the stock's value grows by 1. Each time the coin comes up tails, the stock's value drops by 1.  I then group, say, 50 of these steps into a ""day"", and for each day I look at opening, closing, maximum and minimum. This is then graphed in a candlestick chart.  Funny enough, those things look exactly like the charts analysts look at. Here are a few examples:    If you want to be a troll, show these to a technical analyst and ask them which of these stocks you should sell short and which of them you should buy. You can try this at home, I posted the code here and it only needs Python with a few extra packages (Numpy and Pylab, should both be in the SciPy package). In reply to a comment from JoeTaxpayer, let me add some more theory to this. My code actually performs a one-dimensional random walk. Now Joe in the comments says that an infinite number of flips should approach the zero line, but that is not exactly correct. In fact, there is a high chance to end up far from the zero line, because the expected distance from the start for a random walk with N steps is sqrt(N).  What does indeed approach the zero line is if you took a bunch of these random walks and then performed the average over those. There is, however, one important aspect in which this random walk differs from the stock market: The random walk can go down as far as it likes, whereas a stock has a bottom below which it cannot fall. Reaching this bottom means the company is bankrupt and gets removed from the market. This means that the total stock market, which we might interpret as a sum of random walks, does indeed have a bias towards upwards movement, since I'm only averaging over those random walks that don't go below a certain threshold. But you can really only benefit from this effect by being broadly diversified." I heard a very smart business guy (prof from UPenn) tell us that GE's lack of focus (what does GE do?) probably hurt the stock price.  He said that splitting the company up into multiple more focused companies would probably help overall value.  They'd be more susceptible to variations in the businesses though, so risk to the individual parts would go up.  So I don't know how right that guy was.  GE definitely can't seem to excite the market no matter how many times it tries to reinvent itself. "Diversification is extremely important and the one true ""Free Lunch"" of investing, meaning it can provide both greater returns and less risk than a portfolio that is not diversified. The reason people say otherwise is because they are talking about ""true"" portfolio diversification, which cannot be achieved by simply spreading money across stocks. To truly diversify a portfolio it must be diversified across multiple, unrelated ""Return Drivers."" I describe this throughout my best-selling book and am pleased to provide complimentary links to the following two chapters, where I discuss the lack of diversification from spreading money solely across stocks (including correlation tables), as well as the benefits of true portfolio diversification: Jackass Investing - Myth #8: Trading is Gambling – Investing is Safer Jackass Investing - Myth #20: There is No Free Lunch" I would say the most challenging fact for this assertion is that HFT firms operate with extremely limited capital bases. For a stock with say 10m shares ADV, even a very large and successful HFT strategy might use a position limit of no more than 5000 shares.  That is to say if you sum up and net the buys and sells for a stock across the day the HFT firm will never exceed 10,000 shares (2x position limits assuming it completely flipped) on a stock that trades 10,000,000 shares on a given day. The high volumes are attained through high turnover, the strategy might trade up to 500,000 shares (or 5% of the volume) attaining a 50x turnover.  But that brings me back to the original point. In the market microstructure literature market impact generally has been found to scale linearly or even sub-linearly for net volume executed.   If I alternate between thousands of 1 lot buy and sell orders, it would be very difficult for me to move the market because the market impact of every one of my buy orders roughly cancels the market impact of my almost exactly equal number of sell orders.   There might be a higher-order mechanism at work, but I'm genuinely curious what you think it might be. How could strategies that attain such small net positions have such out-sized impact on market direction?