BlackRock discusses several market structure issues affecting U.S. equity markets and provides several recommendations to further improve market quality and stability. With respect to high-frequency trading, the paper says BlackRock is firmly opposed to predatory HFT practices and says these should be treated as market abuse and policed by regulators. The paper cautions, however, that HFT encompasses a wide variety of trading practices and care must be taken to differentiate predatory practices from practices that benefit investors such as electronic market making and algorithmic execution tools. The paper also comments that HFT should have no negative impact on trading by virtually all retail orders since small orders generally get filled immediately at the National Best Bid and Offer. For institutional investors there is a risk that predatory HFT activity may inflate transaction costs, and for this reason BlackRock uses various tools and strategies to improve the quality of its execution.