There are various uses of the term “readily tradable on an established [securities] market” in the Code that apply to ESOPs and employer securities held in other types of qualified plans. This Notice specifies that the definition under Treasury Regulation §1.401(a)(35)- 1(f)(5) (which discusses diversification requirements for plans that hold publicly-traded employer stock) applies for the purposes of a number of other Code sections that reference the term. (Notice 2011-19).