Twitter said its chief operating officer, Ali Rowghani, has resigned. Reuters

Twitter Inc. (NYSE:TWTR) said its chief operating officer, Ali Rowghani, has resigned, amid reports of an upcoming executive shakeup.

In a Securities and Exchange Commission filing Thursday, Twitter said that Rowghani's resignation was “effective today."

The San Francisco-based social media company said that Rowghani will now serve as a strategic adviser to CEO Dick Costolo.

Rowghani joined Twitter in 2010 as chief financial officer and became COO two years later. Before that, he served as CFO at Pixar Animation Studios.

Twitter said that Rowghani's duties as COO will be shifted to other executives. The company didn't name a successor for Rowghani and didn't give a reason for his departure. Rowghani said in a tweet Thursday that he would "cherish the memories" of his time at Twitter but didn't elaborate on why he's stepping down.

The website Re/code said Wednesday that Twitter was considering shaking up its top management, including a possible shift in duties for Rowghani.

Wednesday, Twitter temporarily took down its popular TweetDeck application after it was hacked to plug a security vunerability.