A company that's originally privately-owned "goes public" when it lists itself on a stock market and sells its shares to the public. It then becomes "publicly-owned", as the true owners of the company are not its directors or executives but its shareholders.
Upon hearing that the company was going public, the investors started speculating how the decision would impact the company's performance.
Going Public refers to an online secret relationship in a social network system (like facebook) between 2 people that is kept in a chat box so their friends are not aware that they are involved with each other. Thay appear as casual friends to the community; Until 1 or both change their relationship status and announce it to the facebook community.
Joan: "did you see, bill and kelly are going public"
Connie: "yes, Bill changed his relationship status on the home page. "