Wash. Rev. Code § 9.47.100
Every person, whether in his or her own behalf, or as the servant, agent, or employee of another person, within or outside of this state, who shall buy or sell for another, or execute any order for the purchase or sale of any commodities, securities, or property, upon margin or credit, whether for immediate or future delivery, shall, upon written demand therefor, furnish such principal or customer with a written statement containing the names of the persons from whom such property was bought, or to whom it has been sold, as the case may be, the time when, the place where, the amount of, and the price at which the same was either bought or sold; and if such person shall refuse or neglect to furnish such statement within forty-eight hours after such written demand, such refusal shall be prima facie evidence as against him or her that such purchase or sale was made in violation of RCW 9.47.090.
RCW 9.47.100