XLK was the first to launch in this space, as such it offers a more narrow focus on the US technology segment. Its S&P 500-only portfolio tilts away from our segment benchmark. XLK is heavily concentrated and also a few that seem like misfits, such as financial payment processers or telecom firms. Its limited selection universe excludes small-caps and most midcaps. Avoiding smaller, less-stable firms results in lower volatility and a tilt toward value compared to our broad tech-industry benchmark index, and can cause other minor performance differences. XLK held the title for a long time as the cheapest and the largest fund in its segment.