How to quantify differences in return with low expense ratio vs high expense ratio mutual funds?
Yes you should take in the expenses being incurred by the mutual fund. This  lists down the fees charged by the mutual fund and where expenses can be found in the annual statement of the fund. To calculate fees and expenses. As you might expect, fees and expenses vary from fund to fund. A fund with high costs must perform better than a low-cost fund to generate the same returns for you. Even small differences in fees can translate into large differences in returns over time. You don't pay expenses, so the money is taken from the assets of the fund. So you pay it indirectly. If the expenses are huge, that may point to something i.e. fund managers are enjoying at your expense, money is being used somewhere else rather than being paid as dividends. If the expenses are used in the growth of the fund, that is a positive sign. Else you can expect the fund to be downgraded or upgraded by the credit rating agencies, depending on how the credit rating agencies see the expenses of the fund and other factors. Generally comparison should be done with funds invested in the same sectors, same distribution of assets so that you have a homogeneous comparison to make. Else it would be unwise to compare between a fund invested in oil companies and other in computers. Yes the economy is inter twined, but that is not how a comparison should be done.
No, some of Vanguard's funds are index funds like their Total Stock Market Index and 500 Index. In contrast, there are funds like Vanguard PRIMECAP and Vanguard Wellington that are actively managed. There are index funds in both open-end and exchange-traded formats. VTI is the ticker for Vanguard's Total Stock Market ETF while VTSMX is an open-end mutual fund format. VOO would be the S & P 500 ETF ticker while VFINX is one of the open-end mutual fund tickers, where VIIIX has a really low expense ratio but a pretty stiff minimum to my mind. As a general note, open-end mutual funds will generally have a 5 letter ticker ending in X while an ETF will generally be shorter at 3 or 4 letters in length. "There are a few reasons why an index mutual fund may be preferable to an ETF: I looked at the iShare S&P 500 ETF and it has an expense ratio of 0.07%.  The Vanguard Admiral S&P 500 index has an expense ratio of 0.05% and the Investor Shares have an expense ratio of 0.17%, do I don't necessarily agree with your statement ""admiral class Vanguard shares don't beat the iShares ETF""." Your investment is probably in a Collective Investment Trust. These are not mutual funds, and are not publicly traded. I.e. they are private to plan participants in your company. Because of this, they are not required* to distribute dividends like mutual funds. Instead, they will reinvest dividends automatically, increasing the value of the fund, rather than number of shares, as with dividend reinvestment. Sine you mention the S&P 500 fund you have tracks closely to the S&P Index, keep in mind there's two indexes you could be looking at: Without any new contributions, your fund should closely track the Total Return version for periods 3 months or longer, minus the expense ratio. If you are adding contributions to the fund, you can't just look at the start and end balances. The comparison is trickier and you'll need to use the Internal Rate of Return (look into the XIRR function in Excel/Google Sheets). *MFs are not strictly required to pay dividends, but are strongly tax-incentivized to do so, and essentially all do. 1: Low fees means: a Total Expense Ratio of less than 0,5%. One detail you may also want to pay attention to whether the fund reinvests returns (Thesaurierender Fonds) which is basically good for investing, but if it's also a foreign-based fund then taxes get complicated, see http://www.finanztip.de/indexfonds-etf/thesaurierende-fonds/ Why would it not make more sense to invest in a handful of these   heavyweights instead of also having to carry the weight of the other   450 (some of which are mostly just baggage)? First, a cap-weighted index fund will invest more heavily in larger cap companies, so the 'baggage' you speak of does take up a smaller percentage of the portfolio's value (not that cap always equates to better performance). There are also equal-weighted index funds where each company in the index is given equal weight in the portfolio. If you could accurately pick winners and losers, then of course you could beat index funds, but on average they've performed well enough that there's little incentive for the average investor to look elsewhere.  A handful of stocks opens you up to more risk, an Enron in your handful would be pretty devastating if it comprised a large percentage of your portfolio. Additionally, since you pay a fee on each transaction ($5 in your example), you have to out-perform a low-fee index fund significantly, or be investing a very large amount of money to come out ahead. You get diversification and low-fees with an index fund. It depends what you mean by 'gain'. Over long period of times the market increases so using a blind monkey with a dart or index fund should be sufficient to get an average returns. The key difference is that changes in currency are close to zero sum game while money in equity or bonds is actually used for something (building a company etc.). If you mean 'get above average returns' then you will likely get answers depending on person. If you think that markets are efficient then you won't beat the market consistently - over long periods the returns are likely to be no better then average - because of large number of 'smart people' trying to beat each other (and even them are likely to have below-average returns). If you don't think so then it is possible to get above average consistently - as long as you know how to beat those 'smart people'. I don't think it has to be either-or. You can profitably invest inside the SIMPLE. (Though I wouldn't put in any more than the 1% it takes to get the match.) Let's look at some scenarios. These assume salary of $50k/year so the numbers are easy. You can fill in your own numbers to see the outcome, but the percentages will be the same. Let it sit in cash in the SIMPLE. You put in 1%, your employer matches with 1%. Your account balance is $1,000 (at the end of the year), plus a small amount of interest. Cost to you is $500 from your gross pay. 100% return on your contributions, yay! Likely 0-1% real returns going forward; you'll be lucky to keep up with inflation over the long term. Short term not so bad. Buy shares of index ETFs in the SIMPLE; let's assume the fee works out to 10%. You put in 1%, employer matches 1%. Your contributions are $500, fees are $100, your balance is $900 in ETFs. 80% instant return, and possible 6-7% real long term returns going forward. Buy funds in the SIMPLE; assume the load is 5%, management fee is 1% and you can find something that behaves like an index fund (so it is theoretically comparable to above). 1% from you, 1% from employer. Your contributions are $500, load fees are $50, your balance is $950. 90% instant return, and possible 5-6% real long term returns going forward (assuming the 6-7% real returns of equities are reduced by the 1% management fee). (You didn't list out the fees, and they're probably different for the different fund choices, so fill in your own details and do the math.) Invest outside the SIMPLE in the same ETFs or equivalent no load index funds; let's assume you can do this with no fees. You put in the same 1% of your gross (ignoring any difference that might come from paying FICA) into a self directed traditional IRA. At the end of the year the balance is $500. So deciding whether or not to take the match is a no brainer: take it. Deciding whether you should hold cash, ETFs, or (one of two types of) funds in your SIMPLE is a little trickier. "The problem I have with this argument is exemplified by the following statement:  *""Focusing on share-restricted hedge funds between 1999 and 2008, Sadka and Ozik found that funds with recent inflows on average earned an additional 5.6 percent annually compared to funds that experienced outflows.*""  Funds that are doing well tend - on average - to see customer inflows.  Funds that are doing poorly tend - on average - to see customer outflows.  It's the concept of ""hot money.""  The authors here imply that it's the fund inflows that prompt the outperformance, when - in reality - outperformance prompts fund inflows."