In 1975, John Bogle founded The Vanguard Group with a mission to simplify stock market investing. The firm offered low-cost index funds, which championed a passive investment approach that tracks the market rather than trying to beat it. Bogle’s indexing philosophy emphasises long-term investing, diversification, and keeping costs low. Most Foolish investors are down with all that, even if they prefer to pick individual stocks (like myself). He once said: “The two greatest enemies of the equity fund investor are expenses and emotions.” Passive investing aims to eliminate high costs and remove emotions from the equation. Here, I’ll look at an exchange-traded fund (ETF) that may be the simplest way to target a seven-figure portfolio. Don’t look for the needle in the haystack. Just buy the haystack! John Bogle I’m talking about the Vanguard FTSE 100 UCITS ETF (LSE: VUKE). As the name indicates, it seeks to track the performance of the FTSE 100 index, which is comprised of large-cap stocks listed in the UK. It therefore invests in all constituents of the Footsie in the same proportion. So, as of 30 April, the top five holdings were: Weighting (%) Shell 9.1% AstraZeneca 8.7% HSBC 6.5% Unilever 5.0% BP 4.2%...