The rationale for equal-weighting is that cap-weighting will have you over-invested in stock sectors that are priced too high. If tech stocks have a huge run an

The rationale for equal-weighting is that cap-weighting will have you over-invested in stock sectors that are priced too high. If tech stocks have a huge run and double their weight in the S&P, do you want them to represent twice as much of your portfolio? If you think the market is efficient you do, otherwise maybe not.