That's the sort of price tag that's far easier for Microsoft (market cap: US$1.6 trillion) to digest than Twitter (valued at around US$29 billion).
But on the plus side, being smaller should make it easier for Twitter to get antitrust approval.
Microsoft has been negotiating with TikTok's Chinese owner, Bytedance, for weeks.
US President Donald Trump says Bytedance must find a buyer for TikTok by September 15 or face a ban.
Last Thursday, Trump signed an executive order saying that after 45 days, the US would prohibit "any transaction by any person" with Bytedance (owner of TikTok) or Tencent (owner of the Chinese social media app WeChat), citing allegations the pair share information with China's government.
However, there were immediate questions over what would constitute a "transaction" with the two no-cost apps, and whether any "ban" could be enforced in practice.
And further complicating matters (or in a parallel universe, simplifying them), a recent CIA report found no evidence that Chinese intelligence authorities could intercept TikTok data or use the app to bore into smartphones.
Whatever happened to the executive order kneecapping Facebook and Twitter?
Trump already faces a credibility problem on the executive order front. Beyond his current controversial attempt to suspend the payroll tax by executive order, on May 28 the President signed an executive order designed to kneecap Facebook and Twitter - both of whom who had recently censored his social media posts.
That order provoked free speech fears as Trump ordered numerous agencies to take action against social media companies, including removing key safe-harbour legal protections around questionable content. But it was framed in broad and some said legally-incoherent terms. Its 30-day and 60-day deadlines have now passed with no Federal agency moving against Facebook or Twitter, both of whom are now actually taking a harder line against Trump - with both deleting a video he posted recently with incorrect claims about children and Covid-19 immunity.
One provision of Trump's May 28 order called for Federal agencies to review their spending on social media and "the statutory authorities available to restrict their receipt of advertising dollars" with 30 days. That could have resulted in some fascinating stats (and been an inadvertent boon for the "fake news" New York Times and other traditional media hated by Trump). But there's no sign of anything having happened on that front.
In the meantime, we've seen the rise of the corporate boycott of Facebook and Twitter of their tepid efforts to remove hate content amid Black Lives Matter protests. So if Federal agencies had in fact followed Trump's executive order, they would have been inadvertently supporting a movement the President loathes. Politics is hard.
Trump, who relies so heavily on social media as a direct conduit to voters, remains emasculated by the fact he needs Twitter and Facebook more than they need him. He has no choice but to swallow their occasional censorship, even though he knows it's doing him damage.
If it is serious about buying TikTok, Twitter's top negotiating tactic could be to drag things out until after November 3, when the interfering Trump might exit stage left.