Open-source software (OSS), which is characterized by licensing arrangements wherein copyright holders grant licensees the ability to freely change and distribute that software, subject to certain requirements or restrictions, has several benefits. These include cost savings, increased customization, access to a collaborative community that provides extensive support and assistance with attracting talent and honing technical employees’ skillsets. Nevertheless, OSS may also pose greater security risks than commercial software, which means that companies must carefully assess the areas in which they seek to utilize OSS. This article, the first in a two-part series, discusses how OSS is being used by financial services companies and analyzes the benefits and risks of OSS. The second article will evaluate actions companies can take to mitigate OSS risks, ways to deal with third-party vendors and due diligence. See our three-part series on a fund manager’s road map to big data: “Its Acquisition and Proper Use” (Aug. 8, 2018); “MNPI, Web Scraping and Data Quality” (Aug. 15, 2018); and “Privacy Concerns, Third Parties and Drones” (Aug. 22, 2018).