NASDAQ will consider a variety of factors including, but not limited to, changes in the: voting power and/or share ownership, management, board of directors, and financial structure of the listed entity. NASDAQ will also consider the nature of the businesses as well as the relative size of the entities involved in the transaction.
There are basically two distinctly different types of "public" shell companies being used to do reverse mergers: "Trading and Reporting" corporations and "Virgin" corporations.
"Trading and Reporting" shell corporations once held an active business. For any number of reasons the business has either ceased to exist or is in a dormant state. It had filed a FORM 10 with the SEC and usually completed an IPO. At its peak, the company's stock was traded on the OTCBB or the Nasdaq National Market.
Go Public Reverse Merger
It is easier to go public without a reverse merger. Reverse mergers are not necessary in the going public process.