Stocks with smaller caps are having their moment. That's great news for this Vanguard ETF."Buy low, sell high" isn't the only way to make money investing. You might want to consider buying high and never selling.The Vanguard Russell 2000 ETF (VTWO 0.59%) hit a record high last week. Over the last three months, the exchange-traded fund (ETF) has significantly more momentum than the S&P 500 (^GSPC 0.44%). Is this Vanguard ETF a buy now?About the Vanguard Russell 2000 ETFBefore we attempt to answer that questi ...