Investors these days are more and more likely to be bombarded by the notion that mutual fund managers must be poor at what they do because the vast majority of these pros fail to surpass the performance of the S&P 500 index, the most commonly used benchmark in judging portfolio proficiency.

The swelling tide of opinion against using fund managers, as opposed to investing in a non-managed fund or ETF that merely mimics the index itself, is often extended even further to argue that all stock investments are inherently unpredictable. If so, fund investors are always much better off in the lowest cost variants, namely index-tracking funds and unmanaged ETFs, since even if a manager is successful in equaling the performance of the index, higher management and trading fees will cause him/her to wind up underperforming the index.

The movement away from managed funds, and toward passive ones, has been gaining more and more adherents. Of course, the longer non-managed funds outperform as compared to managed ones, the more these beliefs will be reinforced. And for quite a while now, and most noteably so far this year, the non-managed funds are beating the pants off managed ones.

As of Nov. 26, while the the S&P 500 index was up 14.3% including dividends, a quick glance at the year-to-date performance of most managed stock funds shows the great majority are up considerably less. In fact, over the last 1, 3, 5, and 10 year periods, the index has beaten the annualized total return of the average US diversified stock fund, as shown below.

So why should anyone want to continue to have any investments in most other funds, except perhaps for a total stock market index fund such as Vanguard Total Stock Market Index (VTSMX) or Vanguard Total Stock Market ETF (VTI) which go beyond including just the biggest capitalization stocks?

Are fund managers really as unable to add value when picking stocks and deciding on these stocks' allocations within their funds as this data seem to suggest? And does this mean that an unmanaged S&P 500 index fund is almost always a smarter long-term investment than most any managed Large Cap fund offered by the myriad of fund companies out there?

Many investors apparently seem to believe so: Aside from investing a whopping $355 billion in VTSMX (whose 25 largest holdings are virtually identical with that of the S&P 500), the next 3 largest funds (which include one ETF), are all S&P 500 variants with a combined total of about $540 billion. By contrast, of all managed funds, the biggest, American Funds Growth Fund of America (AGTHX), checks in at "only" $140 billion. S&P 500-matching funds have certainly become the giants in the room among fund investors.

To answer the above questions, we need to look at a variety of information which will help shed light on the current widely observed performance gap between the S&P index and the majority of managed investments.

What we will find is that many investors overlook certain crucial differences between their S&P index-derived funds and funds competing in the same space as managed ones, other than some of the more obvious, well-known ones. By closely examining these differences as well as the rationales behind them, I believe I can show that many of the arguments leveled against managed funds turn out to be greatly diminished.

Fact 1. Most Large Cap managed funds are not solely invested in US stocks, and therefore, should not perform similarly to S&P-type funds/ETFs.

Of course, the S&P 500 index is invested exclusively in US stocks. But this is not so for the great majority of managed Large Cap stock funds with which a S&P 500 index fund is competing. So why would a fund manager choose to allocate assets elsewhere?

Many widely cited long-term research comparisons have shown that a portfolio that combines U.S. equities with international stocks often performs better than a US-only portfolio with lower overall volatility. Since lower volatility is a plus for most investors, it is easy to see why fund managers often choose to include foreign stocks. In fact, according to the U.S. Securities and Exchange Commission (SEC), one of whose functions is to protect as well as educate investors:

By including exposure to both domestic and foreign stocks in your portfolio, you'll reduce the risk that you'll lose money and your portfolio's overall investment returns will have a smoother ride.

(Italics added; source: http://www.sec.gov/investor/pubs/ininvest.htm).

These benefits are generally a result of diversification and the fact that international stocks sometimes perform better than US stocks.

Therefore, while unmanaged US S&P 500 index-based funds must adhere extremely closely to their index, most managed funds, it would seem, may assume that it is actually in the their investors' best interests (along with the fund company's too, since they obviously prefer to retain investors) to fashion a somewhat more diversified portfolio than just US stocks alone.

Another reason most Large Cap funds (actually, almost all managed funds) aren't totally invested in US stocks:

Usually, most maintain at least a small cash position. Without such cash on hand, whenever a selloff does hit and a potentially above average number of investors choose to bail out, a manager might be forced to sell certain holdings in order to meet the redemptions. Such holdings might be viewed as having long-term potential to do well, but might require being sold at fire-sale prices as a result of the selloff.

Clearly, there may be the need for some sort of a safety mechanism to avoid this, just as an individual investor who must liquidate some investments due to an emergency requiring immediate cash wouldn't want to be forced to sell at a seemingly inappropriate time from his stock portfolio. Some cash on hand can provide that mechanism, but at the expense of potentially losing out on a more profitable investment for the amounts held back.

Unfortunately though, over the last 5 years, both foreign stocks, and of course cash, have severely underperformed US stocks. Therefore, generally speaking, the more a fund allocated to these two areas, the greater the odds that it would have underperformed a S&P index fund/ETF that might have next to nothing in these two areas.

The following data show each area's performance, first so far in 2014, and then for the last five years (annualized; all data below as of Nov. 26):

• Cash (Vanguard Prime Money Market) 0.01, (0.04)
• Non-US Stocks (benchmark: iShares MSCI ACWI ex US ETF) 0.17, (4.72)
• S&P 500 14.26, (15.70)

While allocating a considerable portion of a portfolio outside of US stocks and to cash would not guarantee underperformance in recent years, certainly in terms of probabilities, the higher the combined weighting to these two non-US-stock categories, the more likely a managed portfolio would be dragged down by the lower average performances of foreign stocks and cash.

Let's look at a real example. Consider the recent performance of the Dodge & Cox Stock Fund (DODGX), an outstanding managed fund with long-term managers, who, over the last 15 years, have outperformed the S&P 500 by an average 4.63% per year. Yet, for 2014, the fund is trailing the index by about 3.3%. Does this suggest that perhaps the managers are losing their touch? When we factor in the above considerations, that would not appear to be the case.

Roughly only 1% of the portfolio is being held in cash, so that could hardly be impairing performance much. But what about the 13% or so that is currently held in foreign stocks?

While its 10 largest US holdings as of late November, accounting for about 1/3 of the portfolio are returning 20.2% year-to-date, better than the S&P 500's 14.3% return, it is unlikely that its foreign holdings are doing anywhere near as well given the average severe underperformance of international stocks shown above.

The likely explanation, then, for the subpar recent performance is the fund's decision to invest a moderate amount of its portfolio internationally. If we compare this 13% to that of the largest Large Cap funds by assets, we see that this percent is larger than its competitors. Had the fund chosen not to invest in international stocks, it more than likely would have been able to beat the index.

So, taken together, should you therefore conclude that managed funds that attempt to diversify by adding international stocks and that maintain a cash position are to be avoided?

While the concept of diversification is sound, many investors already have one or more separate funds in their portfolio that meet the need for international exposure. In this case, perhaps a fund such as DODGX may be best for investors who only have that one fund, or perhaps several, but with little or no international exposure.

That said, one must still consider DODGX's outstanding long-term track record. In fact, much of that track record was generated when international stocks were outperforming the S&P, unlike the last 5 years. For example, in the prior half-decade between Oct. 2004 and Oct. 2009, international stocks did outperform the S&P 500 index. Furthermore, even cash in a money market fund outperformed the index as it suffered during the 2007-2009 bear market. According to the Wall Street Journal, the average International stock fund returned 5.8% annualized during that period vs. the S&P's 1.0%

During this period, then, this would of course have most likely helped a more diversified fund that included these assets. And, in fact, during this period, the average US stock fund did outperform the average S&P 500 fund.

This data shows that investors should not assume that a S&P-type index fund will always do better than a managed fund just because this has been true over the last 5 years. Nor should one assume that fund managers are somehow always likely to make market underperforming choices when assembling a portfolio as compared to an unmanaged index.

Fact 2. S&P 500-type funds/ETFs are very heavily weighted to the largest stocks and will only outperform when these largest stocks are outperforming most other stocks; however, historically, smaller cap stocks have outperformed during many extended periods.

Although the S&P 500 index is made up of 500 stocks, it is actually heavily influenced by a much fewer number. The reason is that the construction of the index gives the highest allocations to stocks with largest market capitalizations, such as Apple, Exxon Mobil, Microsoft, Johnson & Johnson, and General Electric. Right now, the performance of these 5 stocks alone will account for about 11% of how the index does on any given day. In fact, the largest 25 stocks in the index account for nearly one third of the daily performance. This overweighting of the largest companies has important implications for investors and for their portfolios if they hold quite a bit of their assets in a S&P 500-type ETF or fund.

Currently, the largest stocks in the overall market are doing the best. The average 2014 return on the above 5 stocks as of late Nov. was 19.2%; the return on the largest 25 stocks was approximately 15.9%. It is easy to see then that the remaining 475 stocks are somewhat underperforming the largest stocks since the entire portfolio is returning 14.3%.

With this the case, it is difficult for a well-diversified mutual fund to outperform the index since such a fund will generally will want to pick from a variety of stocks without closely duplicating the index. However, whenever the largest stocks are not at the top of the performance charts, a more diversified fund can do better.

So a conumdrum for a fund manager develops: Unless he/she also owns primarily these huge, well-performing stocks, it will be difficult for him/her to beat the index. As with including international stocks under Fact 1 above, many managers favor a more diversified allocation that does not always include a heavy weighting toward the largest of the Large Caps as does the "top-heavy" index.

As a likely result of recent underperformance, some fund managers become "closet indexers" to attempt to do as well as the index; they pick the same stocks that are resulting in big gains for the index. But of course, the managed funds have higher fees, pulling them below the index even if they essentially copy it. And seeing the better performance of the index, individual investors themselves move a greater amount to these S&P 500-like funds than they might have otherwise.

The more fund investors move toward index investing, the more the index fund must buy those biggest stocks. This creates a virtuous cycle for these stocks since index fund buying pushes the market caps and prices of the biggest stocks even higher. Even purchases by closet indexers help to push up the prices of these biggest stocks which are then reflected in even higher capitalizations and allocations within the index.

A recent article on bloomberg.com pointed out that fewer individual equities are beating the index than any time since 1999. The average of about 1675 stocks included in the Value Line Arithmetic index was recently up 6.9% this year while the S&P 500 was up 12.1%, both excluding dividends. (Using the actual mean, as opposed to the S&P index's method of giving much bigger weights depending on the total market value of each stock, more closely shows the performance of stocks if you held the stocks in equal amounts. The daily price change of the Value Line Arithmetic Index is calculated by adding the daily percent change of all the stocks, and then dividing by the total number of stocks.)

Will this momentum of the largest stocks always cause the S&P index to outperform as it has done so dramatically thus far this year and to a lesser extent over the last 5 years? Only if these largest of stocks continue to outperform. Once these stocks start lagging, the index will suffer disproportionately and the index will underperform a more balanced portfolio of stocks. In fact, if one goes back 5 and 10 years ago, this is exactly what happened. The average stock fund outperformed the index between Oct. 2004 and Oct. 2009 by about 1% and by about 3% between Oct. 1999 and Oct. 2004, according to data published in the Wall Street Journal. And, in fact, over the full 10 years, the average S&P 500 fund returned slightly less than the average US diversified stock fund.

Fact 3. Index funds do not provide a risk control mechanism, and so index investors who want this will need to provide it for themselves.

This statement is true because in index funds only you are really at the helm; you determine how much risk to bear through your decisions to either be in the fund or not, and if you are in, how much to keep in the fund. The fund operates on auto-pilot, merely by mirroring the changes that occur in the index, out of any one person's control.

When you invest in a managed fund, while you still have ultimate control over your allocation to the fund, the fund manager typically has control over how much of your investment should remain fully invested. If he/she determines that market risk appears too high, the manager can reduce overall exposure to stocks. Further, the manager can control the risk level by avoiding sectors and/or specific stocks that appear too pricey or are currently in free fall and by focusing on those sectors/stocks that do appear to have more favorable forward-looking characteristics. While there is no guarantee that the manager's choices will be correct, an experienced and skilled manager can add value by controlling such risks in a way that an index fund cannot.

It follows that unless you are ready to act on your own behalf to control these risks, perhaps you may want to think twice about investing most, or all, of your money in index funds.

Many managed funds will only buy stocks they consider undervalued, or at least fairly valued. Since many of the largest stocks in the S&P 500 currently do not meet this criterion, managers may be underweight in the overvalued areas. In these recent good years for stocks, the S&P 500 has tended to become more and more loaded with prior winners without regard to valuation. Of course, evaluation of which stocks are at fair value or below, and which are not, and which are not is not something that index funds were designed to do.

However, this is not typically the case for managed funds. A good manager tries to avoid particularly overvalued stocks and concentrate on finding undervalued ones, or, at least, less overvalued ones. While this strategy may not pay off in the short run as the overvalued areas keep running up further, it makes sense to believe that eventually these areas will be stripped of their excessive gains and the undervalued areas will prevail. Unfortunately, though, with so many stocks currently overvalued, it may be difficult for even skilled managers to find alternatives right now.

Note: A companion article to this one, called "Fire Fund Managers? Not So Fast!" is available in my December newsletter on my website (http://funds-newsletter.com)