Does this only affect money invested after June 15th, or does this also devalues money invested before this date? If you don't invest anymore money in the index during the interim rebalancing period refered to by the author, then one should be alright. Right? It's really expensive to get all your marbles out, I'd rather not do it if I don't have to.

Right, you are trapped if you are holding QQQ in a taxable account and have substantial gains, so you should do nothing with the shares you already have. But no, ceasing to invest in it will not save you. The rebalancing discussed in the article happens internally with you already invested dollars.

But do take this moment to realize QQQ never made sense to invest in, and put your future dollars somewhere else. There are plenty of funds that overweight large cap tech but track an index that doesn't care which exchange the stock is listed on.

QQQ rebalances on a schedule. Existing holders are affected because the fund’s underlying composition will change.