A 401k Plan Sponsor is the company or organization that sets up and manages a 401k retirement plan for its employees. This sponsor is usually the employer, and they are responsible for making sure the plan runs smoothly and follows all legal rules. That includes choosing the providers who handle the money, deciding what kind of features the plan offers (like Roth contributions or matching), and keeping everything up to date. While they may get help from professionals, the plan sponsor is ultimately in charge of making sure the plan works in the best interest of the employees who use it to save for retirement.