The growth sector is largely comprised of, in order of importance, technology, healthcare, and retail. I might suggest you going back and looking at a technology index to see which bull-market periods showed a lagging RS line vs. the S&P. Going back to ’11, you will find a 6-8 month period in ’12-’13, depending on which index you use. I once saw (perhaps in his book) where Bill O’Neil wrote that growth will lead a bull about 40% of the time. Since ’11, it has been much more than 40%. I believe this is because of the lower interest-rate environment (growth stocks are sensitive to rates) and the sheer pace of technological innovation. Data from a broad technology index does not go back before ’11, unless one wants to use a semiconductor index which is not an accurate representation of the sector.