Linda Yaccarino, the recently appointed Chief Executive Officer of Twitter, announced via a tweet on Monday evening that she has officially assumed her position at the popular social media platform. The development comes approximately one month after Elon Musk announced her appointment as the new CEO.

"It happened – first day in the books!," she tweeted, without providing further details.

Yaccarino, the former advertising chief at NBCUniversal, is taking over Twitter at a time when the social media platform has been trying to reverse a plunge in advertisement revenues.

Musk, who has served as the CEO since his $44 billion buyout of Twitter last October, previously said that Yaccarino would help build an "everything app."

Former NBCUniversal executive Joe Benarroch also joined Twitter on Monday. He oversaw the communication strategy for the Comcast-owned company's Advertising and Partnerships division, reporting to Yaccarino, before joining Twitter.