Del. Code Ann. tit. 6, § 8-203
After an act or event, other than a call that has been revoked, creating a right to immediate performance of the principal obligation represented by a certificated security or setting a date on or after which the security is to be presented or surrendered for redemption or exchange, a purchaser is charged with notice of any defect in its issue or defense of the issuer, if the act or event:
5A Del. C. 1953, §§ 8-203; 55 Del. Laws, c. 349; 64 Del. Laws, c. 152, § 6; 71 Del. Laws, c. 75, § 1