Financial Dictionary abcdefghijklmnopqrstuvwxyz Search for terms: Principal Protected Note (PPN) A fixed income security that guarantees a return equal to initial investment. Also called Principal-Protected Securities, it is a great solution for risk reluctant investors. Tweet Related Terms Proprietary Trading Proprietary Palladium Platinum Ponzi Scheme Pay Czar Pending Home Sales Index – PHSI Pension Benefit Obligation – PBO Pension Shortfall Perfect Competition