VVTIVanguard Morningstar Total Stock Market ETF

VTI covers the entire US equity market — not only large companies but mid- and small-cap ones too.

The fund tracks a total-market index and holds thousands of securities rather than five hundred. The practical difference from an S&P 500 fund is smaller than it looks: capitalisation weighting means large companies still carry most of the weight, and the thousands of small ones account for a few per cent.

Those few per cent nonetheless change the profile: mid- and small-cap companies behave differently, responding more sharply to the economic cycle and to credit conditions. For an investor building a single broad portfolio this is closer to owning the market than a selected five hundred.

The fee is minimal, portfolio turnover low and tax efficiency high — the fund is designed for long holding rather than trading. Holding it alongside an S&P 500 fund adds little: the overlap is nearly complete.