The Vanguard S&P Mid-Cap 400 Growth ETF (NYSEMKT: IVOG) could be worth considering for growth-focused investors. What is the Vanguard S&P Mid-Cap 400 Growth ETF? The Vanguard S&P Mid-Cap 400 Growth ETF holds a portfolio of lesser-known, fast-growing, smaller companies. This growth stock ETF has a strong track record, with 12.31% average annual returns for the past 15 years. Let's say you invest $500 per month in the Vanguard S&P Mid-Cap Growth ETF, and your investment grows at that same average rate of 12.31% per year.