Twitter Inc co-founders, Jack Dorsey and Evan Williams, and Chief Executive Richard Costolo have informed U.S. regulators that they did not plan to sell the microblogging company's shares after post-IPO restrictions are lifted in May.

Twitter, which debuted on the New York Stock Exchange on Nov. 7, had a 180-day restriction on sale of shares by early investors.

Another Twitter investor, Benchmark, informed regulators that it did not plan to sell the stock before or immediately after the expiration of the lockup period on May 5. (http://r.reuters.com/byg58v)

Benchmark Capital Management is among the top five investors in Twitter.

Twitter's shares, which were priced at $26 each in its IPO, were up 2 percent at $40.95 in early trading on the New York Stock Exchange.