When a company offers its equity shares to the public at large and lists its shares on a stock exchange, it moves from being a privately held or closely held company, to a publicly held company, which agrees to disclose periodic information about its operations and business to the public.
Difference between the price expected by the seller and the price offered by the potential buyer. This is referred to as "bid ask spread" or liquidity risk.
The risk to the shareholder arises if the shares are illiquid and not easily sold at its market value or if the shares are unlisted. The investor's investment may get stuck without an exit option or they may sell their shares at lower than fair value resulting in loss.
The total equity capital required by a company is divided into smaller denomination called the face value or par value of the equity shares. Face value of a share is the value of a company listed in its books and share certificates and is fixed.
The maximum amount of equity capital that a company will have is defined in the Memorandum of Association (MoA) of the company and is called its authorised capital.