Problem: You are looking at your portfolio holistically, as you should, and you seek to invest a determined percentage in a total stock market, lost cost, etf or fund. Your choices available in your 401(k), however, are limited to a S&P 500 Index fund. What to do? Assuming you have other investable assets, the workaround is achieved by using what is called a "completion index" etf.
Two examples are:
VEXMX from Vanguard, expense fee .3%
WXSP from Claymore, expense fee .18%, note that WXSP is relatively new
The completion index tracks the 4500 stocks in the Wilshire 5000 except for the S&P 500. Thus, if you want 40% of your assets invested to track the total stock market as represented by the Wilshire 5000, invest 20% in the S&P 500 in your 401(k) and 20% in a completion etf outside of your 401(k).
The completion index etfs are useful tools for the DIY investor.
If you are seeking investment help, look at the video here on my services. If you are seeking a different approach to managing your assets you have landed at the right spot. I am a fee only advisor registered in the State of Maryland, charge less than half the going rate for investment management, and seek to teach individuals how to manage their own assets using low cost indexed exchange traded funds. Please call or email me if interested in further details. My website is at http://www.rwinvestmentstrategies.com. If you are new to investing, take a look at the "DIY Investor Newbie" posts here by typing "newbie" in the search box above to the left. These take you through the basics of what you need to know in getting started on doing your own investing.