Final answer:
Retail investors are unlikely to attend the annual meeting to vote due to their smaller shareholdings and lesser impact, unlike institutional investors and activist shareholders who typically have a larger stake and greater involvement.
Step-by-step explanation:
The types of shareholders who are unlikely to attend the annual meeting to cast their vote are generally retail investors. These shareholders often hold smaller amounts of stock and may not have a significant financial or decision-making impact on the company, making their participation in the annual meeting less likely. Conversely, institutional investors and activist shareholders are more likely to attend and vote, as they typically hold larger stakes and are more involved in influencing the company's decisions. Preferred stockholders may or may not attend; this can depend on the specific rights attached to their preferred shares, including whether they have voting rights.