Not only does Elon Musk deny being the mysterious creator of bitcoin Satoshi Nakamoto, but he’s also forgotten where he keeps his cryptocurrency.

Musk’s assertions came in response to a blog post coursing through digital-currency sites that suggested the PayPal co-founder and Tesla Inc. chief executive officer himself is probably the bitcoin originator who used the alias Nakamoto.

“Not true,” Musk said Tuesday in a tweet. “A friend sent me part of a BTC a few years, but I don’t know where it is.”

Not true. A friend sent me part of a BTC a few years, but I don’t know where it is.

— Elon Musk (@elonmusk) November 28, 2017

The banter coincides with Bitcoin approaching $10,000 for the first time, bringing this year’s price surge to almost 11-fold even as warnings multiply that the largest digital currency has become an asset bubble. Should it bust the benchmark today, bitcoin’s $167 billion value would exceed that of about 95 percent of the S&P 500 Index members.

The post on Musk, published on the Medium blog platform last week, based its argument on Musk’s technical expertise, comparing him with U.S. inventor and founding father Benjamin Franklin, who also published under a pseudonym. Bitcoin needs Musk’s help, the blog’s author Sahil Gupta said.

“If Elon is Satoshi, it seems like this knowledge would become public at some point anyway,” Gupta wrote. “But if it were public now, Elon could offer guidance as the currency’s ‘founding father.’”

The identity of Satoshi Nakamoto, the pseudonymous author of the research paper that conceived bitcoin about nine years ago, remains a mystery. The name appeared atop the original document that proposed a peer-to-peer electronic cash system.

While speculation over bitcoin’s start is nothing new, conversations in mainstream markets over its rightful place are burgeoning. From Wall Street executives to venture capitalists, observers have been weighing in more frequently, with some more skeptical than others as bitcoin’s rise has grown steeper, sweeping along individual investors.

The number of accounts at Coinbase, one of the largest platforms for trading bitcoin and rival ethereum, has almost tripled to 13 million in the past year, according to Bespoke Investment Group LLC.