Mark Zuckerberg’s control of the board and voting shares at Facebook is not the model favored by Wall Street, but Silicon Valley companies have embraced it. In addition to Facebook, LinkedIn, Zynga, Groupon and Zillow have all used the ownership structure. Meanwhile, Bloomberg reports that Google’s dual-stock structure, which gives its founders more voting control, has been adopted by Twitter, Pinterest Dropbox and Square. [Source: Bloomberg]