When securities, such as bonds, are sold, the delivery date is the date the transaction is completed and the bonds are “delivered” to the new owner. At that point, the new owner may sell the bonds to another investor.
The delivery date is generally a day or more after the trade date, or the day the buyer and seller agree on the transaction. In the past, when stocks and bonds had physical certificates, the delivery date may have lagged further behind the trade date while the certificate was transferred between brokers.