Twitter (TWTR, Tech30) has been an inconsistent stock since its blockbuster initial public offering in November 2013. Shares soared more than 70% on their first day of trading.
A month later, the stock was up nearly 200% from its offering price to over $70 a share. But the stock come tumbling back to Earth since then.
Twitter's stock price was cut in half last year as investors worried about a slowdown in user growth and expressed concerns about the long-term business model.
That's led to some calls for Costolo to be replaced if things don't turn around soon.