Del. Code Ann. tit. 6, § 8-204
A restriction on transfer of a security imposed by the issuer, even if otherwise lawful, is ineffective against a person without knowledge of the restriction unless:
5A Del. C. 1953, §§ 8-204; 55 Del. Laws, c. 349; 64 Del. Laws, c. 152, § 6; 71 Del. Laws, c. 75, § 1