The technological transformation and automation of digital content delivery has revolutionized the media industry. Increased reliance on automation has also led to requirements for standardization of content-delivery formats. This paper examines how the memorability of banner advertising changed with the introduction of new standards regularizing its format. Using data from randomized field tests, we find evidence that for most ads, ad effectiveness falls as the use of standard formats rises. The decline is smaller when a standardized ad appears to be more original (such as ads created by an ad agency). Therefore, a likely explanation is that increased use of a standard format makes it harder for basic ads to distinguish themselves from their competition because the ad format commands less attention. This paper was accepted by Pradeep Chintagunta, marketing.