Got a large cash sum, wanna buy stocks. Should I buy all at once, or spread it over time?
"When you hear advice to buy index funds, that usually comes with two additional pieces of investment discipline advice that are important: These two elements are important to give you relative predictability in your outcome 20 years from now.  In this old blog post of mine I linked to Warren Buffett talking about this, also  mentioned it in a comment on another answer: http://blog.ometer.com/2008/03/27/index-funds/ It's perfectly plausible to do poorly over 20 years if you buy 100% stocks at once, without dollar-cost averaging or rebalancing. It's very very very plausible to do poorly over 10 years, such as the last 10 in fact. Can you really say you know your financial situation in 20-30 years, and for sure won't need that money? Because predictability is important, I like buying a balanced fund and not ""pure stocks"": http://blog.ometer.com/2010/11/10/take-risks-in-life-for-savings-choose-a-balanced-fund/ (feel a little bad linking to my blog, but retyping all that into this answer seems dumb!) Here's another tip. You can go one step past dollar cost averaging and try value averaging: http://www.amazon.com/Value-Averaging-Strategy-Investment-Classics/dp/0470049774 However, chances are you aren't even going to be good about rebalancing if it's done ""by hand,"" so personally I would not do value averaging unless you can find either a fund or a financial advisor to do it for you automatically. (Finance Buff blog makes a case for a financial advisor, in case you like that more than my balanced fund suggestion: http://thefinancebuff.com/the-average-investor-should-use-an-investment-advisor-how-to-find-one.html) Like rebalancing, value averaging makes you buy more when you're depressed about the market and less when it's exciting. It's hard.  (Dollar cost averaging is easily done by setting up automatic investment, of course, so you don't have to do it manually in the way you would with value averaging.) If you read the usual canonical books on index funds and efficient markets it's easy to remember the takeaway that nobody knows whether the market will go up or down, and yes you won't successfully time the market. But what you can do successfully is use an investment discipline with risk control: assume that the market will fluctuate, that both up and down are likely and possible, and optimize for predictability in light of that. Most importantly, optimize to take your emotions and behavior out of the picture. Some disciplines for example are: there are dozens out there, many of them snake oil, I think these I mentioned are valid. Anyway, you need some form of risk control, and putting all your money in stocks at once doesn't give you a lot of risk control. There's no real need to get creative. A balanced fund that uses index funds for equity and bond portions is a great choice." It would depend on a) Ones view on Markets and b) Ones nature. If one believes that the market would be going up in the near future then it would be best to buy all at once. If one believes the market is uncertain, it would make sense to invest over a period of time. If one is a disciplined investor and can stick to plan, it would make sense to invest over a period of time as the risk is generally less. How much less is again subjective. If one is not a disciplined investor then buying now and getting done with is a good idea.   As to exactly quantifying this is absolute number for future would not be possible. One can take the data from past, however it would work advantages if the prices moves up and disadvantages if the price moves down. Depends on what you are, an investor or a speculator. An investor will look at an 'indefinite' investment period. A speculator will be after a fast buck. If you are an investor, buy your stock once as that will cost less commissions. After all, you'll sell your stock in 10, 15, 20 years.
Canadian Couch Potato has an article which is somewhat related. Ask the Spud: Can You Time the Markets? The argument roughly boils down to the following: That said, I didn't follow the advice. I inherited a sum of money, more than I had dealt with before, and I did not feel I was emotionally capable of immediately dumping it into my portfolio (Canadian stocks, US stocks, world stocks, Canadian bonds, all passive indexed mutual funds), and so I decided to add the money into my portfolio over the course of a year, twice a month. The money that I had not yet invested, I put into a money market account. That worked for me because I was purchasing mutual funds with no transaction costs. If you are buying ETFs, this strategy makes less sense. In hindsight, this was not financially prudent; I'd have been financially better off to buy all the mutual funds right at the beginning. But I was satisfied with the tradeoff, knowing that I did not have hindsight and I would have been emotionally hurt had the stock market crashed. There must be research that would prove, based on past performance, the statistically optimal time frame for dollar-cost averaging. However, I strongly suppose that the time frame is rather small, and so I would advise that you either invest the money immediately, or dollar-cost average your investment over the course of the year. This answer is not an ideal answer to your question because it is lacking such a citation. The problem is that short-term trends are really unpredictable.  There is nobody who can accurately predict where a fund (or even moreso, a single stock or bond) is going to move in a few hours, or days or even months. The long-term trends of the entire market, however, are (more or less) predictable.  There is a definite upward bias when you look at time-scales of 5, 10, 20 years and more.  Individual stocks and bonds may crash, and different sectors perform differently from year to year, but the market as a whole has historically always risen over long time scales. Of course, past performance never guarantees future performance.  It is possible that everything could crash and never come back, but history shows that this would be incredibly unlikely.  Which is the entire basis for strategies based on buying and holding (and periodically rebalancing) a portfolio containing funds that cover all market sectors. Now, regarding your 401(k), you know your time horizon.  The laws won't let you withdraw money without penalty until you reach retirement age - this might be 40 years, depending on your current age.  So we're definitely talking long term.  You shouldn't care about where the market goes over a few months if you won't be using the money until 20 years from now. The most important thing for a 401(k) is to choose funds from those available to you that will be as diverse as possible.  The actual allocation strategy is something you will need to work out with a financial advisor, since it will be different for every person.  Once you come up with an appropriate allocation strategy, you will want to buy according to those ratios with every paycheck and rebalance your funds to those ratios whenever they start to drift away.  And review the ratios with your advisor every few years, to keep them aligned with large-scale trends and changes in your life. You shouldn't. The Dow has gained 7% annually on average since October 1915(inflation-adjusted). It has also lost 73% of its inflation-adjusted value from 1966 to 1982 meaning that it would have lost you 4.5% annually for 16 years. Furthermore, past performance is not indicative of future results. If stock markets keep performing like they have for the past 100 years, you can expect there will be a point within the next 60-or-so years your stocks will be higher in value than they were when you bought them. With funds you are paying the people managing them which means you are guaranteed to have pyramiding losses that your gains will have to offset. In your case, you are betting with no fundamental knowledge that S&P will be higher than now whenever you need the money which is not even supported by the above assumption. Dollar averaging just means you will be placing many bets which will reduce your expected losses(and your expected gains) when compared to just buying $100K worth of S&P right now. Whatever you invest in, and whatever your time-frame, don't gamble. If you can't say this company(ies) will be $X more valuable than now in X months with probability > Y, then you shouldn't be investing in it. Nobody ever made money by losing money. There are also safer investments than the stock market, like treasury bonds, even if the returns are lousy. If you know with 100% certainty what the market will do, then invest it all at the best time. If not, spread it out over time to avoid investing it all at the worst possible time. The stock market, as a whole, is extremely volatile.  During any 3 year period, the market could go up or down.  However, and this is the important point,the market as a whole has historically been a good long term investment. If you need the money in 5 years, then you want to put it in something less volatile (so there's less chance of losing it).  If you need the money in 50 years, put it in the market; the massive growth over those 50 years will more than make up for any short term drops, and you will probably come out ahead. Once you get closer to retirement age, you want to take the money out of stocks and put it in something safer; essentially locking in your profit, and protecting yourself from the possibility of further loss. Something else to consider: everyone lost money in 2008.  There were no safe investments (well, ok, there were a few... but not enough to talk about).  Given that, why would you choose another investment over stocks?  Taking a 50% loss after decades of 10% annual returns is still better than a 50% loss after decades of 5% growth (in fact, after 20 years of growth, it's still 250% better - and that ratio will only improve the longer you leave it in). Unless and until you are ready to do the ground work and get your hands dirty in the market, it is better to let the money where it is. But how to distribute money in which asset classes, industry etc is your choice to make. But remember that a big investment company doesn't guarantee that you will always earn a return higher than the market or it is safe with them. They are also bound to make mistakes and go bust, but it would be quite rare for companies, with billions of assets because they have strict checks in place and invest with extreme caution and proper research. One option is to try dabbling in the markets yourself, slowly, not everything at once. You will learn a lot and there are loads of information on the net and books in stores which could get you started. You will need to do a lot of groundwork to beat the market. That is difficult but not impossible. People have done it time and time again and they have put in hard work to do so. And I don't see with a little bit of work and time, why you shouldn't be able to do that, unless and until you are lazy and don't intend to do it. I believe that the Wikipedia article is attempting to draw a difference between dollar cost averaging as a result of investing when money becomes available (i.e. 401k contributions from your paycheck) and spreading out a lump sum investment. For the former you want to continuously invest as the money becomes available following your predetermined plan for allocation. For the later it may be reasonable to consider the market as you decide how and the timing for investing. "This is basically the short-term/long-term savings question in another form: savings that you hope are long-term but which may turn short-term very suddenly. You can never completely eliminate the risk of being forced to draw on long term savings during a period when the market is doing Something Unpleasant that would force you to take a loss (or right before it does Something Pleasant that you'd like to be fully invested during). You can only pick the degree of risk that you're willing to accept, balancing that hazard of forced sales against the lower-but-more-certain returns you'd get from a money market or equivalent. I'm considered a moderately aggressive investor -- which doesn't mean I'm pushing the boundaries on what I'm buying (not by a long shot!), but which does mean I'm willing to keep more of my money in the market and I'm more likely to hold or buy into a dip than to sell off to try to minimize losses. That level of risk-tolerance also means I'm willing to maintain a ready-cash pool which is sufficient to handle expected emergencies (order of $10K), and not become overly paranoid about lost opportunity value if it turns out that I need to pull a few thou out of the investments. I've got decent health insurance, which helps reduce that risk. I'm also not particularly paranoid about the money. On my current track, I should be able to maintain my current lifestyle ""forever"" without ever touching the principal, as long as inflation and returns remain vaguely reasonable. Having to hit the account for a larger emergency at an Inconvenient Time wouldn't be likely to hurt me too much -- delaying retirement for a year or two, perhaps. It's just money. Emergencies are one of the things it's for. I try not to be stupid about it, but I also try not to stress about it more than I must." I know this is heresy but if you have funds for significantly more   than 6 months of expenses (let's say 12 months), how risky would it be   to put it all into stock index funds? Quite risky as if you do need to dip into it, how fast could you get the cash? Also, do you realize the tax implications when you do sell the shares should you have an emergency? In the worst-case scenario, let's say you have a financial emergency   at the same time the stock market crashes and loses half its value.   You could still liquidate the rest and have sufficient funds for 6   months. Am I underestimating the risks of this strategy? That's not worst case scenario though. Worst case scenario would be another 9/11 where the markets are closed for nearly a week and you need the money but can't get the funds converted to cash in the bank that you can use. This is in addition to the potential wait for a settlement in the case of using ETFs if you choose to go that way. In the case of money market funds, CDs and other near cash equivalents these can be accessed relatively easily which is part of the point. A staggered approach where some cash is kept in house, some in accounts that can easily accessed and some in other investments may make sense though the breakdown would differ depending on how much risk people are willing to take. If it truly is an emergency fund then the odds of needing it should be   very slim, so why live with near zero return on that money? Something to consider is what is called an emergency here? For some people a sudden $1,000 bill to fix their car that just broke down is an emergency. For others, there could be emergency trips to visit family that may have gotten into accidents or gotten a diagnosis that they may pass away soon. Consider what do you want to call an emergency here as chances are you may not be considering all that people would think is an emergency. There is the question of what other sources of money do you have to cover should issues arise. If you are comfortable with the risk etc, then the main thing to worry about is diversity.  For some folks, picking stocks is beyond them, or they have no interest in it.  But if it's working for you, and you want to keep doing it, more power to you. If you are comfortable with the risk, you could just as well have ALL your equity position in individual stocks.  I would offer only two pieces of advice in that respect. 1) no more than 4% of your total in any one stock.  That's a good way to force diversity (provided the stocks are not clustered in a very few sectors like say 'financials'), and make yourself take some of the 'winnings off the table' if a stock has done well for you. 2) Pay Strong attention to Taxes! You can't predict most things, but you CAN predict what you'll have to pay in taxes, it's one of the few known quantities.  Be smart and trade so you pay as little in taxes as possible  2A)If you live someplace where taxes on Long term gains are lower than short term (like the USA) then try really really hard to hold 'winners' till they are long term.  Even if the price falls a little, you might be up in the net compared to paying out an extra 10% or more in taxes on your gains.  Obviously there's a balancing act there between when you feel something is 'done' and the time till it's long term.. but if you've held something for 11 months, or 11 months and 2 weeks, odds are you'd be better off to hold till the one year point and then sell it.   2B) Capture Losses when you have them by selling and buying a similar stock for a month or something.  (beware the wash sale rule) to use to offset gains. There are three basic concepts finance (as far as I'm concerned). Liquidity is basically an asset's spendability.  Assets range in liquidity from cash (very liquid) to real estate (not very liquid).  You can spend cash immediately, while real estate must first be converted to cash.   Another important concept is your time horizon.  When do you need your money.  Money you need in the near term should be kept in very liquid assets, while money you won't need for a significantly long time can be tied in to something much less liquid. Volatility is the degree to which an assets value is predictable from day to day.  Cash and guaranteed savings accounts have very low volatility, while a stock portfolio will fluctuate in value from day to day, sometimes a lot and sometimes you can lose your initial investment. So really, you need to determine what you need or want this money for, and depending on when you'll need it you can make decisions about whether or not to invest it, or keep it in a savings account, or keep it in literal actual cash. Your TFSA is maxed for the year, so that's out.  Do you have an emergency fund?  Do you want to travel or have other more near term desires that cost money?  If you have a solid financial foundation and already have an emergency fund, you may want to set up a brokerage account and invest in an index fund.  You should not invest money in the stock market unless you are ready to leave it there for at least a few years.  Stocks are volatile but over a long enough period the market generally goes up. In your search for the right index fund, watch out for fees.  Most big brokers will have a list of funds you can invest in with no up front fees and no commission.  The fund itself will charge an expense ratio, look for an index fund with an expense ratio around 0.10%.  This means you'll pay 0.10% of your holdings each year to the fund manager.   No matter how much money we're talking about, I wouldn't put more than half in the market.  Dip your toe in, get used to the value fluctuating.  Don't start reading about technical analysis and derivative trading.  Just put your money in a very low fee big market index and let it ride. "I'm not sure what you expect in terms of answers, but it depends on personal factors. It pretty well has to depend on personal factors, since otherwise everyone would want to do the same thing (either everyone thinks the current price is one to sell at, or everyone thinks it's one to buy at), and there would be no trades. You wouldn't be able to do what you want, except on the liquidity provided by market makers. Once that's hit, the price is shifting quickly, so your calculation will change quickly too. Purely in terms of maximising expected value taking into account the time value of money, it's all about the same. The market ""should"" already know everything you know, which means that one time to sell is as good as any other. The current price is generally below the expected acquisition price because there's a chance the deal will fall through and the stock price will plummet. That's not to say there aren't clever ""sure-fire"" trading strategies around acquisitions, but they're certain to be based on more than just timing when to sell an existing holding of stock. If you have information that the market doesn't (and assuming it is legal to do so) then you trade based on that information. If you know something the market doesn't that's going to be good for price, hold. If you know something that will reduce the price, sell now. And ""know"" can be used in a loose sense, if you have a strong opinion against the market then you might like to invest based on that. Nothing beats being paid for being right. Finally, bear in mind that expected return is not the same as utility. You have your own investment goals and your own view of risk. If you're more risk-averse than the market then you might prefer to sell now rather than wait for the acquisition. If you're more risk-prone than the market then you might prefer a 90% chance of $1 to 90c. That's fine, hold the stock. The extreme case of this is that you might have a fixed sum at which you will definitely sell up, put everything into the most secure investments you can find, and retire to the Caribbean. If that's the case then you become totally risk-averse the instant your holding crosses that line. Sell and order cocktails." The optimal time period is unambiguously zero seconds.  Put it all in immediately.  Dollar cost averaging reduces the risk that you will be buying at a bad time (no one knows whether now is a bad or great time), but brings with it reduction in expected return because you will be keeping a lot of money in cash for a long time.  You are reducing your risk and your expected return by dollar cost averaging. It's not crazy to trade expected returns for lower risk.  People do it all the time.  However, if you have a pot of money you intend to invest and you do so over a period of time, then you are changing your risk profile over time in a way that doesn't correspond to changes in your risk preferences.  This is contrary to finance theory and is not optimal.  The optimal percentage of your wealth invested in risky assets is proportional to your tolerance for risk and should not change over time unless that tolerance changes. Dollar cost averaging makes sense if you are setting aside some of your income each month to invest.  In that case it is simply a way of being invested for as long as possible.  Having a pile of money sitting around while you invest it little by little over time is a misuse of dollar-cost averaging. Bottom line: forcing dollar cost averaging on a pile of money you intend to invest is not based in sound finance theory.  If you want to invest all that money, do so now.  If you are too risk averse to put it all in, then decide how much you will invest, invest that much now, and keep the rest in a savings account indefinitely.  Don't change your investment allocation proportion unless your risk aversion changes. There are many people on the internet and elsewhere who preach the gospel of dollar cost averaging, but their belief in it is not based on sound principles.  It's just a dogma. The language of your question implies that you may be interested in sound principles, so I have given you the real answer. I suppose it depends on how liquid you need, and if you're willing to put forth any risk whatsoever.  The stock market can be dangerous, but there are strategies out there that will allow you to insure yourself against significant loss, while likely earning you a decent return.  You can buy and sell options along with stocks so that if the stock drops, your loss is limited, and if it goes up or even stays where it's at, you make money (a lot more than 1% annually). Of course there's risk of loss, but if you plan ahead, you can cap that risk wherever you want, maybe 5%, maybe 10%, whatever suits your needs.  And as far as liquidity goes, it should be no more than a week or so to close your positions and get your money if you really need it. But even so, I would only recommend this after putting aside at least a few thousand in a cash account for emergencies. The typical deal is you can put 10% of your gross pay into the ESPP. The purchase will occur on the last deposit date, usually a 6 month period, at a 15% discount to the market price.  So, the math is something like this: Your return if sold the day it's purchased is not 15%, it's 100/85 or 17.6%. Minor nitpick on my part, I suppose.  Also the return is not a 6 month return, as the weekly or bi-weekly deductions are the average between the oldest (6 mo) and the most recent (uh, zero time, maybe a week.) This is closer to 3 months. The annualized rate is actually pretty meaningless since you don't have 4 opportunities to achieve this return, it's important only if the cash flow hit causes you to borrow to support the ESPP purchases. The risk is whether the stock drops the 15% before you can execute the sell to take advantage of the gain.  Of course the return is gross, you need to net for taxes.  Edit to respond to comment below - When I said meaningless, I meant that you can't take the 17.6%, annualize it to 91.2% per year and think your $1000 will compound to $1912. It's as meaningless as when an investor gets a 10% gain on a stock in one day, and (with 250 trading days per year) decides his $1000 will be worth $2 quadrillion dollars after a year. The 17.6% is significant in that it's available twice per year, for a true 38% return over a year, but if borrowing to help the cash flow, that rate is really over 3 months.