Market concentration has reached levels not seen in decades. The three largest U.S. stocks now represent over 20% of the S&P 500’s total value, and the top 20 account for roughly half. iShares Top 20 U.S. Stocks ETF (NYSEARCA:TOPT) offers a direct bet that this ‘winners keep winning’ trend will continue. The Portfolio Role: Concentrated ... Winning Stocks Keep Winning, And That’s What iShares TOPT ETF Let’s You Bet On