Twitter Inc. closed down 9 percent on Wednesday, but it has lost a quarter of its value since the company's first-quarter results were leaked an hour prematurely on Tuesday. But it's not the leak that has caused the massive decline, but rather its contents: The company missed on revenue and lowered its forecast for the remainder of 2015. 

The San Francisco social network's revenue came in at $436 million for the quarter, up 74 percent year over year, but that was far below the $456.52 million investors were expecting. It was also the first time since Twitter went public that revenue did not grow by more than 97 percent on a year-to-year basis.

Twitter Twitter's stock price has lost 25 percent of its value over the last two days due to poor results in the company's first quarter earnings. Photo: Google Finance

The reason for the miss was even more alarming for investors: The company's direct response ad business performed below expectations, and that is a trend Twitter's executives warned will extend into the second quarter and affect the entirety of 2015. As a result, Twitter lowered its annual revenue forecast to the range of $2.17 billion to $2.27 billion, less than the $2.37 billion analysts were expecting. 

It's been a pretty bad two days for Twitter, and already the revenue miss and massive drop in stock price have led some to renew calls for CEO Dick Costolo's head. Prior to the end of 2014, many were already asking that Costolo be replaced due to slow user growth, and now that Twitter's advertising business is showing signs that it may begin plateauing, those calls will only intensify