So it's obvious that a broad-market ETF attempts to imitate the performance of the whole stock market, but what I still don't understand is how it works and exactly what you are investing in when you buy a broad market index.
For example, I'm familiar with the VTI ETF, but it currently only costs $131.96. How can such a relatively small amount of money reflect the performance of the entire New York Stock Exchange? Does the Wilshire 5000, which costs approximately $20k, do a better job of imitating general stock market performance?