What is the term for an allotment of additional shares made to existing members, usually in proportion to their existing holdings?

The correct term for an allotment of additional shares made to existing members in proportion to their existing holdings is a rights issue. In a rights issue, shareholders have the opportunity to purchase additional shares at a predetermined price, typically lower than the market price, in order to maintain their proportional ownership in the company. This mechanism is often employed by companies to raise capital while allowing current shareholders to avoid dilution of their investment.

In contrast to a rights issue, a bonus issue refers to shares given to existing shareholders without any cost, based on their current holdings, thereby increasing the number of shares they own without requiring them to invest further. A bonus redeemable issue is a more specific financial instrument that involves conditions under which the shares can be redeemed, typically not associated with a straightforward allotment to maintain ownership proportions. Class A share issue specifies a category of shares that may confer different rights compared to other classes but does not inherently involve the concept of proportional allotment to existing stakeholders.

Thus, the rights issue is distinct as it primarily focuses on giving existing shareholders the chance to buy more shares proportionally to their current investment, directly affecting share capital and ownership stakes in a meaningful way.