Lock-up periods prevent company insiders from selling stock following an initial public offering. CEO Dick Costolo and co-founders Jack Dorsey and Evan Williams have said that they have no plans to sell their stock when the lock-up expired, 180 days after Twitter's initial public offering.
Still, Twitter's stock fell nearly 11 percent on Tuesday, to $34.61. Earlier, shares hit their lowest point ever at $34.55.
Twitter went public on Nov. 7. The stock later soared as high as $74.73.
San Francisco-based Twitter's latest earnings report surpassed expectations, but worries about user growth and engagement weighed on its stock.