Cal. Commercial Code § 9206

(a) A security interest in favor of a securities intermediary attaches to a person’s security entitlement if both of the following conditions are satisfied: (1) The person buys a financial asset through the securities intermediary in a transaction in which the person is obligated to pay the purchase price to the securities intermediary at the time of the purchase. (2) The securities intermediary credits the financial asset to the buyer’s securities account before the buyer pays the securities intermediary. (b) The security interest described in subdivision (a) secures the person’s obligation to pay for the financial asset. (c) A security interest in favor of a person that delivers a certificated security or other financial asset represented by a writing attaches to the security or other financial asset if both of the following conditions are satisfied: (1) The security or other financial asset satisfies both of the following: (A) In the ordinary course of business it is transferred by delivery with any necessary endorsement or assignment. (B) It is delivered under an agreement between persons in the business of dealing with those securities or financial assets. (2) The agreement calls for delivery against payment. (d) The security interest described in subdivision (c) secures the obligation to make payment for the delivery.