Read also: Bytedance Must Divest Assets, Future of TikTok in US Remains Uncertain
Trump claims that TikTok could be used by China to track the locations of federal employees, build dossiers on people for blackmail and conduct corporate espionage.
In late August, China's commerce ministry published new rules potentially making it more difficult for ByteDance to sell TikTok to a US entity by adding "civilian use" to a list of technologies that are restricted for export.
ByteDance had vowed to "strictly abide" by new export rules.
"We believe Microsoft would only buy TikTok WITH its core algorithm which the Chinese government and ByteDance was not willing to budge," Wedbush analyst Daniel Ives said in a note.
"Given the need now to get a green light from Beijing after its export rules were changed a few weeks ago, TikTok's days in the US likely are numbered with a shutdown now the next step," the analyst said.
Downloaded 175 million times in the United States, TikTok is used by as many as a billion people worldwide to make quirky, short-form videos on their cellphones. It has repeatedly denied sharing data with Beijing.
Microsoft said it would have "made significant changes to ensure the service met the highest standards for security, privacy, online safety, and combatting disinformation".
A deal with Microsoft could also have included Walmart, which joined forces with the tech giant in negotiations.