The U.S. Options Security Master dataset provides a root-level reference catalog of all listed and delisted U.S. options disseminated via OPRA, covering options on equities, ETFs, ETNs, indexes, and currencies from 2012 to the present. Each record represents an option root security and includes summary attributes such as option type, settlement type, underlying symbol, and underlying security type. This dataset is designed to define the structural identity of an option root, rather than individual expirations or strikes. The security master is organized using algoseek’s persistent algoseek Security Identifier (ASID). The ASID remains stable throughout the lifecycle of an option root, even as individual contracts (strikes and expirations) are listed and expire. This enables consistent root-level mapping and simplifies integration across downstream options datasets. The dataset is delivered as a single, consolidated file and is updated daily. Companion lookup files are available to map ASID to option root symbols and underlying symbols, supporting efficient identifier resolution and cross-dataset joins.