Elon Musk has claimed he has “acquired Twitter” in a post to the social network reassuring advertisers it will stay a safe place for their brands, amid fears one of his first actions as chief executive will be to restore Donald Trump’s account. After months of uncertainty over whether or not his $44bn acquisition of the social media platform would go through, the Tesla chief executive’s post is the strongest acknowledgment yet that the deal is expected to be sealed before its deadline of 5pm in Delaware on Friday. Musk wrote in a statement attached to the tweet: “The reason I acquired Twitter is because it is important to the future of civilisation to have a common digital town square, where a wide range of beliefs can be debated in a healthy manner, without resorting to violence.” He added: “That is why I bought Twitter. I didn’t do it because it would be easy. I didn’t do it to make more money. I did it to try to help humanity, whom I love.” Despite his use of the past tense, he did not legally own Twitter at the time of the post and the company continued to trade on the New York stock exchange. The final paperwork is expected to be completed on Friday afternoon. He published the tweet a day after visiting the company’s headquarters in San Francisco and posting a video of himself entering the building while carrying a sink, with the caption: “Entering Twitter HQ – let that sink in!” On Wednesday, Musk also changed his Twitter handle to “Chief Twit”. In a sign of market confidence that the purchase will now go ahead, the platform’s shares rose by 1% on Thursday to $53.90, close to the $54.20 a unit agreed price. However, Musk’s note also underscores the long-term fallout of his aggressive negotiations, which have seen him denigrate Twitter’s published user figures and promise an almost moderation-free experience after the purchase. Despite Musk being the world’s richest man, Twitter’s revenue will have to stay high even as a private company: the loans he has taken out to buy it will lead to an interest bill of about $1bn a year, which he will need to pay out of the platform’s profits. Musk said in his tweet: “There is currently great danger that social media will splinter into far right wing and far left wing echo chambers that generate more hate and divide our society … That said, Twitter obviously cannot become a free-for-all hellscape, where anything can be said with no consequences! “In addition to adhering to the laws of the land, our platform must be warm and welcoming to all, where you can choose your desired experience according to your preferences, just as you can choose, for example, to see movies or play video games ranging from all ages to mature.” He added: “Fundamentally, Twitter aspires to be the most respected advertising platform in the world that strengthens your brand and grows your enterprise. To everyone who has partnered with us, I thank you. Let us build something extraordinary together.” Although Musk did not acknowledge it, the message was apparently prompted by an earlier report in the Wall Street Journal suggesting advertisers considered the return of Trump to the site a “red line”. A dozen clients of one agency had issued orders to pause all adverts on Twitter if the former US president’s account was reinstated, the paper reported. In a now deleted tweet sent in April, just after his first offer to buy Twitter, Musk wrote that his plans for the platform included “no ads”. He wrote: “The power of corporations to dictate policy is greatly enhanced if Twitter depends on advertising money to survive.”