Dictionary:

unsubscribe

  (ŭn'sŭb-skrīb')

To cancel a subscription, especially to an online publication, service, or mailing list.

To cancel the subscription of (a subscriber): Please unsubscribe me from your mailing list.

To cancel a service. It is often possible to unsubscribe to an e-mail service by typing the word "unsubscribe" into a reply message. Contrast with subscribe. See opt-out.

Newly issued securities that have not seen much interest, or subscriptions, from investors ahead of the issue date or have not been offered by brokerages. If you wanted to own the newly issued shares, you'd only be able to purchase them as you would any other stock through the secondary markets.

Investopedia Says:
Essentially, you can view a subscription to a public offering as an order to purchase the shares from your brokerage firm once they are issued. If you are not subscribed to a given public issue, you will not be buying any shares through the public offering.

The investment bank handling a public offering tries to determine which offering price will result in an optimal number of subscriptions for the issue. Too high an offering price would likely result in the shares being unsubscribed.

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