What is the function of a Unanimous Shareholder Agreement?

A Unanimous Shareholder Agreement (USA) primarily functions to restrain the power of directors, allowing shareholders to exert more influence over corporate governance. In many corporate structures, directors typically have the authority to make significant decisions without needing to obtain shareholder approval. However, a USA shifts some of this authority, granting shareholders the ability to make decisions that directors may otherwise control. This arrangement can set forth specific limitations on the powers of directors or dictate how certain decisions are to be made, thus reinforcing the shareholders' role in governance.

While the other options encompass important aspects of corporate law and governance, they do not capture the primary function of a USA. Shareholder voting power is generally determined by share ownership and is not inherently equitable through a USA. Managing corporate expenses is more aligned with operational management rather than shareholder governance. Additionally, while a USA can facilitate the sale of shares by setting out certain conditions or rights of first refusal, this is a secondary function and not the main purpose of such an agreement.