Shelf Registration

What Does Shelf Registration Mean?
A regulation that a corporation can evoke to comply with U.S. Securities and Exchange Commission (SEC) registration requirements for a new stock offering up to three years before doing the actual public offering. However, the corporation must still file the required annual and quarterly reports with the SEC.

In terms of SEC regulations, it is formally known as SEC Rule 415.

Investopedia explains Shelf Registration
Sometimes current market conditions are not favorable for a specific firm to issue a public offering. For example, suppose the housing market is heading toward a dramatic decline. In this case, it may not be a good time for a home builder to come out with its second offering, as many investors will be pessimistic about companies working in that sector. By using shelf registration, the firm can fulfill all registration-related procedures beforehand and go to market quickly when conditions become more favorable.