John, I am intrigued by your question. ETFs that hold big stocks are typically quite diversified across sectors and industries. Given that, your question never would have to mind.
Second, you say you own many ETFs. I can imagine why anyone. would need to own more that 4-6 ETFs at anyone time, given that most are diversified investments.
About 12 years ago, AAII created a model portfolio made up of just ETFs. Every quarter, they reported to the members on the performance of the model portfolio for years and years. They made changes to the model perhaps only once a year. Eventually, they abandoned it, on the grounds that they couldn't get it to out-perform the S&P 500 Index. - - - So, an investor (like you) needs to develop a portfolio strategy that is going to out-perform the S&P 500 Index over the long run. If not, why go to the trouble? You might as well own just VOO.
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JAMES GRANT
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