The collection and use of big data can provide many benefits for fund managers and others, but can also present new and complex risks, especially when the data sets contain PII. This final article in our three-part series discusses big-data risk, including risks related to privacy, the use of third-party data and drones, as well as recommended methods for mitigating those risks. The first article explored the big-data landscape, along with how fund managers can acquire and use big data in their businesses. The second article analyzed issues and best practices surrounding the acquisition of material nonpublic information, web scraping and the quality and testability of data. See also “Using Big Data Legally and Ethically While Leveraging Its Value (Part One of Two)” (May 17, 2017); Part Two (May 31, 2017).