Investors are often reminded that a portfolio must always stay diversified. For those who don't want to be involved with individual stock picking, the usual S&P 500 ETFs are often recommended, since they have become the staple way of long-term wealth creation, with exposure to 500 different companies. However, as the American large-caps have outrun the rest of the market over the past few months, the top 10 stocks in terms of weight in, say, SPY currently occupy nearly 30% of its total holdings.
(Source: ETF.com)
Therefore, the argument can be made that investing