; or (II) 5 percent of the revenues earned by the person's ultimate parent entity during the preceding 12-month period; or (ii) if the person who committed the violation has unfair leverage, 5 percent of the revenues earned by the person's ultimate parent entity during the preceding 12-month period. (F) Rulemaking (i) In general The Commission may promulgate in accordance with section 553 of title 5, United States Code, such rules as may be necessary to carry out this section, including guidelines regarding what constitutes an exceptional market shock or that provide for additional characteristics that demonstrate that a person has unfair leverage. (ii) Required guidance Not later than 180 days after the date of enactment of this Act, the Commission shall promulgate regulations regarding violations of this section, which shall include guidelines on, for the purposes of this Act, what constitutes a market, a grossly excessive price for a good or service, and an excessive price for a good or service. (iii) Definition of grossly excessive price (I) In general For purposes of subsection (a) and the guidance described in clause (ii), the Commission shall define the term grossly excessive price , which shall include— (aa) subject to subclause (II), a price for a good or service that is equal to an amount not less than 20 percent greater than the average price for such good or service in the market during the 6-month period preceding the sale or offer that allegedly violates subsection (a)