Chinese tech billionaire Jack Ma, who co-founded the giant Alibaba Group, is worth around US$44.4 billion, according to Forbes.
As the former executive chairman of the company, sometimes called the Amazon of China, he met with ex-US President Donald Trump to discuss a million potential jobs and has entertained at events by performing as Michael Jackson.
But since standing down from the board of Alibaba in October last year, Ma has all but disappeared from public view, with much speculation as to his well being and what involvement the Chinese authorities may be playing in his absence.
That's related to a speech he gave on October 24 in which he criticised the authorities for, among other things, the banking rules and their interference with businesses.
He referred to them as an "old people's club", saying "the game in the future is about innovation, not just regulatory skills". Ma concluded China didn't have experts who could make appropriate policies to drive that.
Days later his other company The Ant Group - the world's largest Fintech company - was due to have its initial public offering (IPO).
The IPO was valued at US$37 billion and had been oversubscribed 870 times with US$2.8 trillion of orders for shares in China, Forbes reported. But Ma was instead summoned to Beijing for some "re-education".
"Regulatory interviews" were conducted, according to the Chinese press, with the company reporting "views regarding the health and stability of the financial sector were exchanged".
The next day Ant's IPO was abruptly cancelled and Ma hasn't been seen since. "We mean being actually observed, and verifiably photographed, in public, and at liberty," Forbes says.
He was missing from the final episode of Africa's Business Heroes, his own talent show, and removed from the show's website. He stopped posting on social media too, with no updates on his Twitter account since October.
According to Forbes, Ma has been sighted just six times since then, all of them "strange, suspiciously vague, and indirect".
That includes a carefully stage-managed video to an unseen audience in a rural public school that lasted just 43 seconds and a video call with Vladimir Putin.
In the latter, Ma appeared as one of eight other people in Putin's 90-minute call to the Russian Geographical Society. He didn't speak, didn't smile and is never referred to, says Forbes.
Other sightings are second-hand reports, text exchanges and speculation over whether Ma was present when his private jet logged flights. But Ma hasn't been photographed in all that time, and with one billion smartphones in China that doesn't seem right, Forbes says.
"Given his notoriety and the intense vested interest of the financial world in his status and wellbeing, if he is at liberty today, how could it be that there are no pictures of him in circulation?"
In the nine months since Ma's speech, regulators in China have cracked down on his businesses, with orders on Ant to reduce the value of its money market and Alibaba being fined US$2.8 billion for antitrust violations.
Alibaba was told to "rectify its behaviour" and also make the business smaller. Hundreds of billions of dollars have been wiped off the valuation of the company, too.
And the speculation continues. Ma's love of painting has been talked about, with some saying he is deliberately lying low.
But only if - or indeed when - Ma finally reappears are we likely to get answers to where he's been and what he's been doing.