Update (4:25 p.m.): Updated with Tuesday market close information.
NEW YORK (TheStreet) -- Twitter (TWTR - Get Report) fell more than 17.5% to an all-time low of $31.72 on Tuesday amid the expiration of a six-month share lock-up period that had prevented the sale of approximately 82% of the company's outstanding equity.
The likely sell-off would likely put even more pressure on the stock, which has been declining since April 29 when the social media company reported weak quarterly results. Twitter has met its revenue targets in both quarters since its IPO on Nov. 7, 2013, but concerns about user growth and levels of engagement has eliminated $18 billion of market value, or approximately half of its market capitalization.
Twitter co-founders Jack Dorsey and Evan Williams and CEO Dick Costolo said in April they had no intentions to sell their shares after the lock-up expired. But other shareholders could very well sell their stake, especially because none of the insiders sold their stock during the IPO.
The stock continued to drop in after-market activity. More than 134 million shares changed hands, which dwarfed the average volume of 13,251,000.