VO tracks the CRSP US Mid Cap Index, covering approximately 340 US companies in the middle capitalization tier — larger than small-caps but smaller than the S&P 500 mega-caps. Mid-caps occupy an interesting strategic position: they are large enough to have established businesses with institutional-quality management and financial resources, yet small enough to still deliver growth rates that large-caps cannot achieve at their scale. They have historically delivered strong long-term returns — often matching or exceeding large-caps over full cycles while exhibiting less volatility than small-caps. Mid-cap companies span a range of industries, with good representation in industrials, healthcare, financials, technology and consumer sectors that is often more balanced than the technology-heavy large-cap indexes. At 0.04% expense ratio, VO is extremely cost efficient. The mid-cap allocation is frequently underrepresented in investor portfolios that hold both a large-cap fund and a small-cap fund without specific mid-cap coverage. For investors, VO fills that gap efficiently — adding companies in the growth sweet spot that are too large for most small-cap indexes and not yet large enough to dominate large-cap ones, providing a complementary allocation that improves diversification across the US equity size spectrum.
