Topic: How To Invest

Q: I recently read that the hugely over-priced Tesla has been added to the S&P 500. Since I have a significant portion of my retirement funds in an S&P 500 ETF, I am concerned that the value of the ETF will be dragged down once (I think) the Tesla valuation comes down out of orbit. Should I rebalance my holdings to decrease exposure to the S&P 500? Thanks!

Article Excerpt

A: Certainly, if one stock becomes an outsized part of a market capitalization-weighted ETF, then you need to consider adjusting your overall holdings. That’s especially so if that ETF also makes up a significant part of your portfolio. Meanwhile, you always need to keep the “Nortel factor” in mind. Most market indexes are set up so that the weight of a company in the index depends on its total value compared to the total value of all the companies in the index. Consequently, if you run your portfolio to match an index, you’ll always buy more of stocks that go up and sell some of your holdings of stocks that go down. This may improve your results a little from time to time. It can also backfire dramatically. For instance, in 2001, a craze of sorts developed in the shares of Nortel Networks Corp. The stock soared far above the rest of the market and came to represent 37% of the value of…