Factbox: Who will get rich from Twitter's IPO?

SAN FRANCISCO (Reuters) - Twitter is preparing to sell 70 million shares to the public in an IPO that will value the company at $10.9 billion. Below is a list of the number of shares owned by some of the people and investment firms that will benefit most from the offering: Executive officers and directors: Evan Williams, 56,909,847 shares, or 12 percent. Williams was Twitter's CEO until 2010, when current chief Dick Costolo took the helm. He is now working on a publishing platform, Medium, dedicated to long-form content. Williams will have a 10.4 percent stake after selling shares in the IPO, according to the company's most recent prospectus. Jack Dorsey, 23,453,017 shares, or 4.9 percent. Dorsey co-founded Twitter and still serves as its chairman. In 2009, he founded payments service Square and serves as its CEO. Dorsey will have a 4.3 percent stake after the IPO. Dick Costolo, 7,675,239 shares, or 1.6 percent. A onetime improvisational comedian, Costolo took the helm of Twitter in 2010. He joined Twitter as COO the year before, after he and co-founders sold their web feed management provider FeedBurner to Google in 2007. Costolo will have a 1.4 percent stake after the offering. Adam Bain, 1,785,818 shares, or less than 1 percent. Bain is the president of global revenue at Twitter. He was formerly the president of audience network at News Corp's Fox Interactive Media. David Rosenblatt, 291,666 shares, or less than 1 percent. Rosenblatt is the CEO of luxury online retailer 1stdibs.com and is a member of Twitter's board of directors. The following groups own at least 5 percent: Rizvi Traverse Management and affiliates, 85,171,093 shares, or 17.9 percent. A closely held private-equity fund based in Michigan, Rizvi has made a name for itself by buying stakes in entertainment companies such as Playboy and movie producer Summit Entertainment. Last year, it led a $200 million funding round in Jack Dorsey's payments company, Square. The group will have a 15.6 percent stake in Twitter after the IPO. Spark Capital and affiliates, 32,414,224 shares, or 6.8 percent. Venture firm Spark started investing in Twitter in 2008. For a time, Spark partner Bijan Sabet served on Twitter's board. The group will have a 6 percent stake after the IPO. Benchmark, 31,567,052 shares, or 6.6 percent. Venture firm Benchmark started investing in Twitter in 2009 when it was valued in the $200 million-$250 million range. Benchmark will have a 5.8 percent stake after the IPO. Union Square Ventures and affiliates, 27,838,992 shares, or 5.9 percent. Venture firm Union Square started investing in Twitter in 2008. For a time, USV partner Fred Wilson served on Twitter's board. The group will have a 5.1 percent stake after the sale. DST Global and affiliates, 23,744,745 shares, or 5 percent. The investment firm founded by Russian billionaire Yuri Milner led a $400 million investment in Twitter in 2011. At the time, Twitter was valued at around $8 billion. The group will have a 4.4 percent stake after the IPO. (Reporting by Alexei Oreskovic; Editing by Joseph Radford)