Twitter parts with four key executives

SAN FRANCISCO -- Four of Twitter's key executives are leaving the company in an exodus that has escalated the uncertainty facing the messaging service as it struggles to broaden its audience and lure back disillusioned investors.

Twitter CEO Jack Dorsey announced the management shake-up late Sunday after technology news site Re/Code reported the changes earlier in the day.

Dorsey described the departures as voluntary, a characterization three of the four exiting executives echoed in their posts.

The upheaval leaves Twitter without its top engineering executive, Alex Roetter; its top products executive, Kevin Weil; head of human resources, Skip Schipper; and Katie Stanton, who oversaw the company's media partnerships.

Dorsey is turning over supervision of the human resources and media teams to Twitter's chief operating officer, Adam Bain, and assigned engineering to the company's chief technology officer, Adam Messinger. Bain and Messinger will share some of the responsibilities for creating and running Twitter's various products.

This is the second major fissure in Twitter's ranks since Dorsey was named the San Francisco company's permanent CEO in October. His hiring followed a three-month stint as interim CEO after the resignation of his predecessor, Dick Costolo.

In one of his first moves, Dorsey laid off more than 300 employees, or about 8 percent of Twitter's workforce, to trim expenses at a company that has never turned a profit since its service began nearly a decade ago.

It's not unusual for CEOs to reshuffle management shortly after their arrival.

But analysts interpreted Twitter's changes as a distress signal instead of a reason to hope the company is starting to head in the right direction.

"We don't see how the departure of the heads of three major business divisions can be viewed as a positive in the middle of an attempted business turnaround," Stifel analyst Scott Devitt wrote in a research note.

Devitt had been recommending Twitter's stock before the management departures prompted him to reverse his opinion.

In another note, Citi analyst Mark May said the defections may prolong Dorsey's attempt to turn around Twitter and could hint at problems that may surface Feb. 10 when the company is scheduled to report its results for the final three months of last year.

Twitter's stock shed 82 cents, or more than 4 percent, to close Monday at $17.02.

The shares have plunged by 53 percent since Dorsey became interim CEO last July, pushing them well below their price of $26 when they were sold in an initial public offering in November 2013.