Is diversification better
"There are probably 3-4 questions here.  Diversification - A good index, a low cost S&P fund or ETF can serve you very well. If you add an extended market index or just go with ""Total market"", that might be it for your stock allocation. I've seen people with 5 funds, and it didn't take much analysis to see the overlap was so significant, that the extra 4 funds added little, and 2 of the 5 would have been it. If you diversify by buying more ETFs or funds, be sure to see what they contain.  If you can go back in time, buy Apple, Google, Amazon, etc, and don't sell them. Individual stocks are fun to pick, but unless you put in your homework, are tough to succeed at. You need to be right at the buy side, and again to know if, and when, to sell. I bought Apple, for example, long ago, pre-last few splits. But, using responsible a approach, I sold a bit each time it doubled. Has I kept it all through the splits, I'd have $1M+ instead of the current $200K or so of stock. Can you tell which companies now have that kind of potential for the future?  The S&P has been just about double digit over 60 years. The average managed fund will lag the S&P over time, many will be combined with other funds or just close. Even with huge survivor bias, managed funds can't beat the index over time, on average. Aside from a small portion of stocks I've picked, I'm happy to get S&P less .02% in my 401(k). In aggregate, people actually do far worse due to horrific timing and some odd thing, called emotions." "Diversification tends to protect you from big losses. But it also tends to ""protect"" you from big gains. In any industry, some companies provide good products and services and prosper while others have problems and fail. (Or maybe the winners are just lucky or they paid off the right politicians, whatever, not the point here.) If you put all your money in one stock and they do well, you could make a bundle. But if you pick a loser, you could lose your entire investment. If you buy a little stock in each of many companies, then some will go up and some will go down, and your returns will be an average of how everyone in the industry is doing. Suppose I offered to bet you a large sum of money that if I roll a die, it will come up 6. You might be reluctant to take that bet, because you can't predict what number will come up on one roll of a die. But suppose I offered to bet you a large sum of money that a die will come up 6, 100 times in a row. You might well take that bet, because the chance that it will turn up 6 time after time after time is very low. You reduce risk by spreading your bets. Anyone who's bought stock has surely had times when he said, ""Oh man! If only I'd bought X ten years ago I'd be a millionaire now!"" But quite a few have also said, ""If only I'd sold X ten years ago I wouldn't have lost all this money!""  I recently bought a stock a stock that within a few months rose to 10 times what I paid for it ... and then a few months later the company went bankrupt and the stock was worth nothing. I knew the company was on a roller coaster when I bought the stock, I was gambling that they'd pull through and I'd make money. I guessed wrong. Fortunately I gambled an amount that I was willing to lose." "Diversification is the only real free lunch in finance (reduction in risk without any reduction in expected returns), so clearly every good answer to your question will be ""yes.""  Diversification is good.""  Let's talk about many details your question solicits. Many funds are already pretty diversified.  If you buy a mutual fund, you are generally already getting a large portion of the gains from diversification.  There is a very large difference between the unnecessary risk in your portfolio if you only hold a couple of stocks and if you hold a mutual fund.  Should you be diversified across mutual funds as well?  It depends on what your funds are.  Many funds, such as target-date funds, are intended to be your sole investment.  If you have funds covering every major asset class, then there may not be any additional benefit to buying other funds. You probably could not have picked your ""favorite fund"" early on.  As humans, we have cognitive biases that make us think we knew things early on that we did not.  I'm sure at some point at the very beginning you had a positive feeling toward that fund.  Today you regret not acting on it and putting all your money there.  But the number of such feelings is very large and if you acted on all those, you would do a lot of crazy and harmful things.  You didn't know early on which fund would do well.  You could just as well have had a good feeling about a fund that subsequently did much worse than your diversified portfolio did. The advice you have had about your portfolio probably isn't based on sound finance theory.  You say you have always kept your investments in line with your age.  This implies that you believe the guidelines given you by your broker or financial advisor are based in finance theory.  Generally speaking, they are not.  They are rules of thumb that seemed good to someone but are not rigorously proven either in theory or empirics.  For example the notion that you should slowly shift your investments from speculative to conservative as you age is not based on sound finance theory.  It just seems good to the people who give advice on such things.  Nothing particularly wrong with it, I guess, but it's not remotely on par with the general concept of being well-diversified.  The latter is extremely well established and verified, both in theory and in practice.  Don't confuse the concept of diversification with the specific advice you have received from your advisor. A fund averaging very good returns is not an anomaly--at least going forward it will not be.  There are many thousand funds and a large distribution in their historical performance.  Just by random chance, some funds will have a truly outstanding track record.  Perhaps the manager really was skilled.  However, very careful empirical testing has shown the following: (1) You, me, and people whose profession it is to select outperforming mutual funds are unable to reliably detect which ones will outperform, except in hindsight  (2) A fund that has outperformed, even over a long horizon, is not more likely to outperform in the future. No one is stopping you from putting all your money in that fund. Depending on its investment objective, you may even have decent diversification if you do so.  However, please be aware that if you move your money based on historical outperformance, you will be acting on the same cognitive bias that makes gamblers believe they are on a ""hot streak"" and ""can't lose.""  They can, and so can you. ======== Edit to answer a more specific line of questions =========== One of your questions is whether it makes sense to buy a number of mutual funds as part of your diversification strategy.  This is a slightly more subtle question and I will indicate where there is uncertainty in my answer.   Diversifying across asset classes.  Most of the gains from diversification are available in a single fund.  There is a lot of idiosyncratic risk in one or two stocks and much less in a collection of hundreds of stocks, which is what any mutual fund will hold.  Still,you will probably want at least a couple of funds in your portfolio.  I will list them from most important to least and I will assume the bulk of your portfolio is in a total US equity fund (or S&P500-style fund) so that you are almost completely diversified already. Risky Bonds.  These are corporate, municipal, sovereign debt, and long-term treasury debt funds. There is almost certainly a good deal to be gained by having a portion of your portfolio in bonds, and normally a total market fund will not include bond exposure.  Bonds fund returns are closely related to interest rate and inflation changes.  They are also exposed to some market risk but it's more efficient to get that from equity.  The bond market is very large, so if you did market weights you would have more in bonds than in equity.  Normally people do not do this, though.  Instead you can get the exposure to interest rates by holding a lesser amount in longer-term bonds, rather than more in shorter-term bonds.  I don't believe in shifting your weights toward nor away from this type of bond (as opposed to equity) as you age so if you are getting that advice, know that it is not well-founded in theory.  Whatever your relative weight in risky bonds when you are young is should also be your weight when you are older. International. There are probably some gains from having some exposure to international markets, although these have decreased over time as economies have become more integrated.  If we followed market weights, you would actually put half your equity weight in an international fund.  Because international funds are taxed differently (gains are always taxed at the short-term capital gains rate) and because they have higher management fees, most people make only a small investment to international funds, if any at all. Emerging markets  International funds often ignore emerging markets in order to maintain liquidity and low fees.  You can get some exposure to these markets through emerging markets funds.  However, the value of public equity in emerging markets is small when compared with that of developed markets, so according to finance theory, your investment in them should be small as well.  That's a theoretical, not an empirical result. Emerging market funds charge high fees as well, so this one is kind of up to your taste.  I can't say whether it will work out in the future. Real estate.  You may want to get exposure to real estate by buying a real-estate fund (REIT).  Though, if you own a house you are already exposed to the real estate market, perhaps more than you want to be.  REITs often invest in commercial real estate, which is a little different from the residential market. Small Cap.  Although total market funds invest in all capitalization levels, the market is so skewed toward large firms that many total market funds don't have any significant small cap exposure.  It's common for individuals to hold a small cap fund to compensate for this, but it's not actually required by investment theory.  In principle, the most diversified portfolio should be market-cap weighted, so small cap should have negligible weight in your portfolio.  Many people hold small cap because historically it has outperformed large cap firms of equal risk, but this trend is uncertain.  Many researchers feel that the small cap ""premium"" may have been a short-term artifact in the data.  Given these facts and the fact that small-cap funds charge higher fees, it may make sense to pass on this asset class.  Depends on your opinion and beliefs. Value (or Growth) Funds.  Half the market can be classed as ""value"", while the other half is ""growth.""  Your total market fund should have equal representation in both so there is no diversification reason to buy a special value or growth fund.  Historically, value funds have outperformed over long horizons and many researchers think this will continue, but it's not exactly mandated by the theory.  If you choose to skew your portfolio by buying one of these, it should be a value fund. Sector funds.  There is, in general, no diversification reason to buy funds that invest in a particular sector.  If you are trying to hedge your income (like trying to avoid investing in the tech sector because you work in that sector) or your costs (buying energy because you buy use a disproportionate amount of energy) I could imagine you buying one of these funds. Risk-free bonds.  Funds specializing in short-term treasuries or short-term high-quality bonds of other types are basically a substitute for a savings account, CD, money market fund, or other cash equivalent.  Use as appropriate but there is little diversification here per se. In short, there is some value in diversifying across asset classes, and it is open to opinion how much you should do.  Less well-justified is diversifying across managers within the same asset class.  There's very little if any advantage to doing that."
Another disadvantage is the inability to value commodities in an accounting sense. In contrast with stocks, bonds and real estate, commodities don't generate cash flows and so any valuation methodology is by definition speculative. But as rhaskett notes, there are diversification advantages. The returns for gold, for instance, tend to exhibit low/negative correlation with the performance of stocks. The question is whether the diversification advantage, which is the primary reason to hold commodities in a multi-asset class portfolio through time, overcomes the disadvantages? The answer... maybe. "The calculation and theory are explained in the other answers, but it should be pointed out that the video is the equivalent of watching a magic trick.  The secret is: ""Stock A and B are perfectly negatively correlated.""  The video glasses over that fact that without that fact the risk doesn't drop to zero. The rule is that true diversification does decrease risk. That is why you are advised to spread year investments across small-cap, large-cap, bonds, international, commodities, real estate. Getting two S&P 500 indexes isn't diversification.  Your mix of investments will still have risk, because return and risk are backward calculations, not a guarantee of future performance. Changes that were not anticipated will change future performance. What kind of changes: technology, outsourcing, currency, political, scandal." The question is not whether CFA charterholders are better investment managers but rather whether starting (or having completed) your CFA will land you a better job. It's been my experience that it does, which is why so many people pursue it "I recommend you take a look at this lecture (really, the whole series is enlightening), from Swenson. He identifies 3 sources of returns: diversification, timing and selection. He appears to discard timing and selection as impossible. A student kinda calls him out on this. Diversification reduces risk, not increase returns. It turns out they did time the market, by shorting .com's before the bubble, and real estate just before the downturn. In 1990, Yale started a ""Absolute Return"" unit and allocated like 15 percent to it, mostly by selling US equities, that specializes in these sorts of hedging moves. As for why you might employ managers for specific areas, consider that the expense ratio Wall Street charges you or me still represent a very nice salary when applied to the billions in Yale's portfolio. So they hire internally to reduce expenses, and I'm sure they're kept busy. They also need people to sell off assets to maintain ratios, and figuring out which ones to sell might take specialized knowledge. Finally, in some areas, you functionally cannot invest without management. For example, Yale has a substantial allocation in private equity, and by definition that doesn't trade on the open market. The other thing you should consider is that for all its diversification, Yale lost 25 percent of their portfolio in 2009. For a technique that's supposed to reduce volatility, they seem to have a large range of returns over the past five years." Asset Allocation serves many purposes, not just mitigating risk via a diversification of asset classes, but also allowing you to take a level of risk that is appropriate for a given investor at a given time by how much is allocated to which asset classes. A younger investor with a longer timeframe, may wish to take a lot more risk, investing heavily in equities, and perhaps managed funds that are of the 'aggressive growth' variety, seeking better than market returns. Someone a little older may wish to pull back a bit, especially after a bull market has brought them substantial gains, and begin to 'take money off the table' perhaps by starting to establish some fixed income positions, or pulling back to slightly less risky index,  'value' or 'balanced' funds. An investor who is near or in retirement will generally want even less risk, going to a much more balanced approach with half or more of their investments in fixed income, and the remainder often in income producing 'blue chip' type stocks, or 'income funds'.  This allows them to protect a good amount of their wealth from potential loss at a time when they have to be able to depend on it for a majority of their income. An institution such as Yale has very different concerns, and may always be in a more aggressive 'long term' mode since 'retirement' is not a factor for them.  They are willing to invest mostly in very aggressive ways, using diversification to protect them from one of those choices 'tanking' but still overall taking a pretty high level of risk, much more so than might be appropriate for an individual who will generally need to seek safety and to preserve gains as they get older.  For example look at the PDF that @JLDugger linked, and observe the overall risk level that Yale is taking, and in addition observe the large allocations they make to things like private equity with a 27%+ risk level compared to their very small amount of fixed income with a 10% risk level.  Yale has a very long time horizon and invests in a way that is atypical of the needs and concerns of an individual investor.  They also have as you pointed out, the economy of scale (with something like #17B in assets?) to afford to hire proven experts, and their own internal PHD level experts to watch over the whole thing, all of which very few individual investors have. For either class of investor, diversification, is a means to mitigate risk by not having all your eggs in one basket.  Via having multiple different investments (such as picking multiple individual stocks, or aggressive funds with different approaches, or just an index fund to get multiple stocks) you are protected from being wiped out as might happen if a single choice might fail.  For example imagine what would have happened if you had in 2005 put all your money into a single stock with a company that had been showing record profits  such as Lehman Brothers, and left it there until 2008 when the stock tanked. or even faster collapses such as Enron, etc that all 'looked great' up until shortly after they failed utterly.   Being allocated across multiple asset classes provides some diversification all on it's own, but you can also be diversified within a class. Yale uses the diversification across several asset classes to have lower risk than being invested in a single asset class such as private equity. But their allocation places much more of their funds in high risk classes and much less of their funds in the lowest risk classes such as fixed income. "Diversification is spreading your investments around so that one point of risk doesn't sink your whole portfolio. The effect of having a diversified portfolio is that you've always got something that's going up (though, the corollary is that you've also always got something going down... winning overall comes by picking investments worth investing in (not to state the obvious or anything :-) )) It's worth looking at the different types of risk you can mitigate with diversification:  Company risk This is the risk that the company you bought actually sucks. For instance, you thought gold was going to go up, and so you bought a gold miner.  Say there are only two -- ABC and XYZ.  You buy XYZ. Then the CEO reveals their gold mine is played out, and the stock goes splat. You're wiped out. But gold does go up, and ABC does gangbusters, especially now they've got no competition.  If you'd bought both XYZ and ABC, you would have diversified your company risk, and you would have been much better off. Say you invested $10K, $5K in each. XYZ goes to zero, and you lose that $5K. ABC goes up 120%, and is now worth $11K. So despite XYZ bankrupting, you're up 10% on your overall position.  Sector risk You can categorize stocks by what ""sector"" they're in. We've already talked about one: gold miners. But there are many more, like utilities, bio-tech, transportation, banks, etc. Stocks in a sector will tend to move together, so you can be right about the company, but if the sector is out of favor, it's going to have a hard time going up.    Lets extend the above example. What if you were wrong about gold going up? Then XYZ would still be bankrupt, and ABC would be making less money so they went down as well; say, 20%. At that point, you've only got $4K left. But say that besides gold, you also thought that banks were cheap. So, you split your investment between the gold miners and a couple of banks -- lets call them LMN and OP -- for $2500 each in XYZ, ABC, LMN, and OP. Say you were wrong about gold, but right about banks; LMN goes up 15%, and OP goes up 40%.  At that point, your portfolio looks like this: XYZ start $2500 -100% end $0 ABC start $2500 +120% end $5500 LMN start $2500 +15% end $2875 OP start $2500 +40% end $3500 For a portfolio total of: $11,875, or a total gain of 18.75%.  See how that works?  Region/Country/Currency risk So, now what if everything's been going up in the USA, and everything seems so overpriced? Well, odds are, some area of the world is not over-bought. Like Brazil or England. So, you can buy some Brazilian or English companies, and diversify away from the USA. That way, if the market tanks here, those foreign companies aren't caught in it, and could still go up. This is the same idea as the sector risk, except it's location based, instead of business type based.  There is an additional twist to this -- currencies.  The Brits use the pound, and the Brazilians use the real. Most small investors don't think about this much, but the value of currencies, including our dollar, fluctuates. If the dollar has been strong, and the pound weak (as it has been, lately), then what happens if that changes? Say you own a British bank, and the dollar weakens and the pound strengthens. Even if that bank doesn't move at all, you would still make a gain.  Example: You buy British bank BBB for 40 pounds a share, when each pound costs $1.20. Say after a while, BBB is still 40 pounds/share, but the dollar weakened and the pound strengthened, such that each pound is now worth $1.50. You could sell BBB, and because of the currency exchange once you've got it converted back to dollars you'd have a 25% gain.   Market cap risk Sometimes big companies do well, sometimes it's small companies. The small caps are riskier but higher returning. When you think about it, small and mid cap stocks have much more ""room to run"" than large caps do. It's much easier to double a company worth $1 billion than it is to double a company worth $100 billion.  Investment types Stocks aren't the only thing you can invest in. There's also bonds, convertible bonds, CDs, preferred stocks, options and futures. It can get pretty complicated, especially the last two. But each of these investment behaves differently; and again the idea is to have something going up all the time.  The classical mix is stocks and bonds. The idea here is that when times are good, the stocks go up; when times are bad, the bonds go up (because they're safer, so more people want them), but mostly they're there to providing steady income and help keep your portfolio from cratering along with the stocks. Currently, this may not work out so well; stocks and bonds have been moving in sync for several years, and with interest rates so low they don't provide much income.  So what does this mean to you? I'm going make some assumptions here based on your post. You said single index, self-managed, and don't lower overall risk (and return). I'm going to assume you're a small investor, young, you invest in ETFs, and the single index is the S&P 500 index ETF -- SPY.  S&P 500 is, roughly, the 500 biggest companies in the USA. Further, it's weighted -- how much of each stock is in the index -- such that the bigger the company is, the bigger a percentage of the index it is.  If slickcharts is right, the top 5 companies combined are already 11% of the index! (Apple, Microsoft, Exxon, Amazon, and Johnson & Johnson). The smallest, News Corp, is a measly 0.008% of the index.  In other words, if all you're invested in is SPY, you're invested in a handfull of giant american companies, and a little bit of other stuff besides.  To diversify: Company risk and sector risk aren't really relevant to you, since you want broad market ETFs; they've already got that covered. The first thing I would do is add some smaller companies -- get some ETFs for mid cap, and small cap value (not small cap growth; it sucks for structural reasons). Examples are IWR for mid-cap and VBR for small-cap value.   After you've done that, and are comfortable with what you have, it may be time to branch out internationally. You can get ETFs for regions (such as the EU - check out IEV), or countries (like Japan - see EWJ). But you'd probably want to start with one that's ""all major countries that aren't the USA"" - check out EFA.  In any case, don't go too crazy with it. As index investing goes, the S&P 500 is not a bad way to go. Feed in anything else a little bit at a time, and take the time to really understand what it is you're investing in.  So for example, using the ETFs I mentioned, add in 10% each IWR and VBR. Then after you're comfortable, maybe add 10% EFA, and raise IWR to 20%. What the ultimate percentages are, of course, is something you have to decide for yourself.  Or, you could just chuck it all and buy a single Target Date Retirement fund from, say, Vanguard or T. Rowe Price and just not worry about it." "It depends on what you're talking about. If this is for your retirement accounts, like IRAs, then ABSOLUTELY NOT! In your retirement accounts you should be broadly diversified - not just between stocks, but also other markets like bonds. Target retirement funds and solid conservative or moderate allocation funds are the best 'quick-and-dirty' recommendation for those accounts. Since it's for the long haul, you want to be managing risk, not chasing returns. Returns will happen over the 40 or so years they have to grow.  Now, if you're talking about a taxable stock account, and you've gotten past PF questions like ""am I saving enough for retirement"", and ""have I paid off my debt"", then the question becomes a little more murky.  First, yes, you should be diversified. The bulk of how a stock's movement will be in keeping with how its sector moves; so even a really great stock can get creamed if its sector is going down. Diversification between several sectors will help balance that.  However, you will have some advantage in this sector. Knowing which products are good, which products everybody in the industry is excited about, is a huge advantage over other investors. It'll help you pick the ones that go up more when the sector goes up, and down less when the sector goes down. That, over time and investments, really adds up. Just remember that a good company and a good stock investment are not the same thing. A great company can have a sky-high valuation -- and if you buy it at that price, you can sit there and watch your investment sink even as the company is growing and doing great things. Have patience, know which companies are good and which are bad, and wait for the price to come to you.  One final note: it also depends on what spot you are in. If you're a young guy looking looking to invest his first few thousand in the market, then go for it. On the other hand, if you're older, and we're talking about a couple hundred grand you've got saved up, then it's a whole different ball of wax. It that spot, you're back to managing risk, and need to build a solid portfolio, at a measured pace." Investopedia has a nice article on this here The Key benefit looks like better returns with lower capital. The disadvantage is few brokers offering that can be trusted. Potentially lower return due to margins / spreads. Higher leverage and can become an issue. Diversification is an important aspect of precious metals investing.  Therefore I would suggest diversifying in a number of different ways: "Of course. ""Best"" is a subjective term. However relying on the resources of the larger institutions by pooling with them will definitely reduce your own burden with regards to the research and keeping track. So yes, investing in mutual funds and ETFs is a very sound strategy. It would be better to diversify, and not to invest all your money in one fund, or in one industry/area. That said, there are more than enough individuals who do their own research and stock picking and invest, with various degrees of success, in individual securities. Some also employe more advanced strategies such as leveraging, options, futures, margins, etc. These advance strategies come at a greater risk, but may bring a greater rewards as well. So the answer to the question in the subject line is YES. For all the rest - there's no one right or wrong answer, it depends greatly on your abilities, time, risk tolerance, cash available to invest, etc etc." "An asset allocation formula is useful because it provides a way to manage risk. Rebalancing preserves your asset allocation. The investment risk of a well-diversified portfolio (with a few ETFs or mutual funds in there to get a wide range of stocks, bonds, and international exposure) is mostly proportional to the asset class distribution. If you started out with half-stocks and half-bonds, and stocks surged 100% over the past few years while bonds have stayed flat, then you may be left with (say) 66% stocks and 33% bonds. Your portfolio is now more vulnerable to future stock market drops (the risk associated with stocks). (Most asset allocation recommendations are a little more specific than a stock/bond split, but I'm sure you can get the idea.) Rebalancing can be profitable because it's a formulaic way to enforce you to ""buy low, sell high"". Massive recessions notwithstanding, usually not everything in your portfolio will rise and fall at the same time, and some are actually negatively correlated (that's one idea behind diversification, anyway). If your stocks have surged, chances are that bonds are cheaper. This doesn't always work (repeatedly transferring money from bonds into stocks while the market was falling in 2008-2009 could have lost you even more money). Also, if you rebalance frequently, you might incur expenses from the trading (depending on what sort of financial instrument you're holding). It may be more effective to simply channel new money into the sector that you're light on, and limit the major rebalancing of the portfolio so that it's just an occasional thing. Talk to your financial adviser. :)" Diversifying your portfolio between asset A and asset B only reduces the portfolio risk if asset A and asset B are not correlated. If they have either a low correlation or a negative correlation to each other, then you benefit from combining them in a portfolio in terms of risk reduction. The standard deviation of returns will be lower in a portfolio of low or uncorrelated assets. If on the other hand you combine two correlated assets into a portfolio you are doubling down on the same assumption, which means you are not reducing your risk. You are also wasting capital because now you have allocated capital to 2 separate trades / investments yet they have shown a high tendency of moving together. Here is an article that discusses this further: Why Diversify your Stock Portfolio In my original question, I  was wondering if there was a mathematical convention to help in deciding on whether an equity offering OR debt offering would be a better choice. I should have clarified better in the question, I used Vs. which may have made it unclear. Pro:  - Faces less redemption pressure and hence the Fund Manager can focus more on long term gains rather than immediate gains.  - Works well in emerging markets.  - Less churn out in case the market falls sharply, there by making more money in long run. Cons:  - No additional money to invest/take advantage of market situation.  - Less liquid for investor as he is locked in for a period. Unfortunately I believe there is not a good answer to this because it's not a well posed problem.  It sounds like you are looking for a theoretically sound criteria to decide whether to sell or hold.  Such a criteria would take the form of calculating the cost of continuing to hold a stock and comparing it to the transactions cost of replacing it in your portfolio. However, your criteria for stock selection doesn't take this form.  You appear to have some ad hoc rules defining whether you want the stock in your portfolio that provide no way to calculate a cost of having something in your portfolio you don't want or failing to have something you do want.  Criteria for optimally rebalancing a portfolio can't really be more quantitative than the rules that define the portfolio.