Elon Musk ended his first week as Twitter’s owner with an indelible mark by slashing, by some estimates, up to half of the company’s workforce with little notice and cutting off employees’ access. Many employees spent the day tweeting their goodbyes, as Musk revealed brands had begun pulling their advertisements, leading to what he said was a “massive drop in revenue”. Audi, General Motors, General Mills and Pfizer were among those who halted advertisements , amid concerns Musk will scale back misinformation and security protections on the platform. Advertising accounts for 90% of Twitter’s revenues. Reports in previous days had suggested the company had made plans to cut as many as half of its 7,500 workers worldwide, and employee statements on Friday suggested some teams had taken large hits. Just four days before the US midterm elections, in which hundreds of politicians are running for election, there were claims Twitter’s “entire” curation team had been affected, potentially jeopardizing the company’s ability to counter misinformation, with one moderator warning of a risk content could become “more toxic”. Reports indicate that the public relations team responsible for managing communications with journalists and other organizations has also seen deep cuts. Other groups that have been dissolved, according to members of those departments, include the company’s human rights team as well as the machine learning and algorithmic ethics teams. Some staff awoke on Friday to find they were locked out of their laptops and their access to the company Gmail and Slack had been revoked. Chris Younie, who works for Twitter in entertainment partnerships in the UK, tweeted: “Well this isn’t looking promising. Can’t log into emails. Mac won’t turn on. But so grateful this is happening at 3am. Really appreciate the thoughtfulness on the timing front guys … ” One employee told the Guardian that the platform could not “function as usual” on Friday because so many members of staff had been locked out of their employee work accounts. The cuts come as the company’s new billionaire owner scrambles to turn a profit one week after he purchased the platform for $44bn, a far higher cost than it was valued. Last month, Musk had said he was “obviously overpaying for Twitter right now”. Meanwhile, organizers including the NAACP are pushing advertisers to consider pausing their spending, citing fears over content moderation and hate speech on the platform. Several companies have already done so. Musk blamed “activist groups pressuring advertisers”, accusing activists of “trying to destroy free speech in America”. The trend, however, appears to have started with the advertisers themselves. Musk also claimed there hadn’t been any changes to content moderation, despite internal sources reporting the curation team had been gutted. That team playsa key role in coverage of “civic integrity” events such as elections, breaking news and sports, ensuring users have vetted information presented as moments, trends and topics products. It is viewed internally as a key filter against misleading posts. The employee added that flags from partner news organisations about possible misinformation on the platform were going unanswered. “The platform is likely to become more toxic with less healthy information to counter the disinformation or misinformation narratives,” said the employee, who was speaking on condition of anonymity. Twitter’s policy on misleading content includes labelling contentious posts or flagging contextualising information next to such posts. The employee said they had been informed by email that their position was under review. Staff had been informed in an email on Thursday they would receive word about their employment status by the following day. “In an effort to place Twitter on a healthy path, we will go through the difficult process of reducing our global workforce,” the email said. “We recognize that this will impact a number of individuals who have made valuable contributions to Twitter, but this action is unfortunately necessary to ensure the company’s success moving forward.” “Looks like I’m unemployed y’all. Just got remotely logged out of my work laptop and removed from Slack. #OneTeam forever. Loved you all so much. So sad it had to end this way,” tweeted one former Twitter employee. The firings have already prompted legal action in the US. In the UK, union leaders compared Musk’s moves to the controversial firing of 800 P&O ferry workers this year and called for the government to act. Mike Clancy, general secretary of Prospect, which represents tech workers, said: “Twitter is treating its people appallingly. The government must make clear to Twitter’s new owners that we won’t accept a digital P&O and that no one is above the law in the UK, including big tech barons.” Musk has already fired the company’s top executives, including the former CEO Parag Agrawal. He also removed the company’s board of directors and installed himself as the sole board member. The sackings come at a difficult moment for Musk, who paid $44bn for the company and last month said he was “obviously overpaying for Twitter right now”. Musk has called himself a “free speech absolutist” and his takeover has been celebrated by many on the right who believed Twitter’s former leadership was censoring them. Immediately after his takeover, trolls flooded the service with hate speech. The sudden nature of the layoffs may also have fallen foul of California employment law and already looks set to land Musk in court. The Worker Adjustment and Retraining Notification (Warn) statute requires employers with at least 100 workers to disclose layoffs involving 500 or more employees, regardless of whether a company is publicly traded or privately held. Barry White, a spokesperson for California’s employment development department, said on Thursday the agency had not received any such notifications from Twitter. A class-action lawsuit was filed on Thursday in federal court in San Francisco on behalf of one employee who was laid off and three others who were locked out of their work accounts. It alleges that Twitter intends to lay off more employees and has violated the law by not providing the required notice. The prominent trial lawyer Lisa Bloom said she had been in contact with many Twitter employees now facing redundancy. “Elon Musk has a history of violating California’s labor laws, as Tesla has been hit with a shocking number of sexual and racial harassment lawsuits. His workers are human beings who are all entitled to respectful treatment. This time a hard-hitting class-action lawsuit will finally educate him that even the world’s richest man is not above the law,” she said. Simon Balmain, a former senior community manager at Twitter, told the Guardian he was “shocked, but not surprised” at the sudden job cuts at the tech firm. Balmain, who had worked at the company for a year, said: “I had finished work but still had my laptop open and we all received an email from the company about a reduction in head count. An hour after that my laptop flashed and was wiped, I no longer had access to my apps.” He said that the suddenness of removing such a large chunk of the workforce overnight didn’t come as a huge shock as he had heard “credible rumours” that job cuts were coming and that the staff were “braced for impact”. Balmain said Musk’s comments since he indicated an interest to buy the company had been “bad for morale” at the firm. He added: “I’ve spoken to a few people in the same position as me and what is very apparent is we had a very good corporate culture and since the news people have been really looking out for each other, including a number of former employees who have reached out and offered their support.”