Twitter is a publicly traded company and is owned by its shareholders. The largest shareholders as of 2021 are institutional investors such as Vanguard Group, BlackRock, and Morgan Stanley.

The company was founded in 2006 by Jack Dorsey, Biz Stone, and Evan Williams, who were also early investors. However, they have since sold a significant portion of their shares and do not hold majority ownership.

Twitter's ownership structure is governed by its board of directors, which includes CEO Jack Dorsey and other prominent business leaders such as Martha Lane Fox and Bret Taylor. The board is responsible for making strategic decisions for the company and overseeing its management.

In summary, Twitter is owned by its shareholders, with institutional investors holding the largest stake. The company's ownership structure is governed by its board of directors, which includes its CEO and other prominent business leaders.