Preferred shares are more common in private or pre-public companies, where it is useful to distinguish between the control of and the economic interest in the company. Government regulations and the rules of stock exchanges may either encourage or discourage the issuance of publicly traded preferred shares. In many countries, banks are encouraged to issue preferred stock as a source of Tier 1 capital. On the other hand, the Tel Aviv Stock Exchange prohibits listed companies from having more than one class of capital stock.