Bird, the e-scooter rental startup that earned a $2 billion valuation within a year of launching, is one of the fastest startups in history to achieve unicorn status. After raising a total of $450 million in venture capital in three rounds, Bird founder and CEO Travis VanderZanden has already sold off some of his shares.

According to the Information, which broke the story, Bird's amount of founder preferred stock decreased by a third, from 7 percent of the company's total stock down to about 4 percent. The sale could've been worth as much as $44 million if the shares were sold at the same price as during the company's most recent fundraising round. The details of the sale were confirmed by a company filing provided by a private data firm, Lagniappe Labs.

A source familiar with the deal confirmed the sale with Inc., explaining that VanderZanden sold some of his shares during the latest Series C round. The source said he sold them because the round was "oversubscribed" and he "wanted to make room for additional, strategic investors." The sale was approved, and supported by, the board.

A company spokesperson would not comment on the sale. VanderZanden, who launched Bird after working as an executive for both Lyft and Uber, contributed his own capital to the $3 million seed round before the company launched in September 2017.

The selling of shares this early in a company's life is odd. Founders usually hold on to their equity to signal confidence in the company's future.

While e-scooter companies like Bird and competitors Lime and Spin initially caused havoc in cities across the U.S., the fast-emerging category is thought to be the next battleground for VC-backed alternative-transportation startups. Lyft and Uber, multiple outlets report, are also planning to launch their own programs.