The Oaktree Capital co-chairman who called cryptocurrencies “not real” in July appears to be rethinking his earlier position.

In a new investor note published September 7, Howard Marks revisited the topic he explored earlier this summer, when at the time he dubbed cryptocurrencies “an unfounded fad” that had created a high-risk market bubble.

Marks still thinks the cryptocurrency market is in bubble territory, but he acknowledged in the note that the “particularly spirited response” to his remarks caused him to rethink his earlier approach. After walking through the characteristics that make something a currency – that it’s accepted for exchange and serves as a store of value – Marks ultimately agrees that bitcoin qualifies as one in this regard.

He wrote:

“Bitcoin fans argue that it qualifies as a currency under these criteria: most importantly, it’s something that parties can agree to accept as legal tender and a store of value. That actually seems right.”

That said, he’s not completely convinced about the cryptocurrency market’s long-term prospects, according to the note. On this point, he highlights the proliferation of other cryptocurrencies, wondering aloud “who knows which one will turn out to be the winner?”

All the same, Marks concluded that while his perspective on cryptocurrencies has shifted, he doesn’t plan on putting any money in the market either.

“I think I understand what a digital currency is, how bitcoin works, and some of the arguments for it. But I still don’t feel like putting my money into it, because I consider a speculative bubble,” he wrote, adding:

“I’m willing to be proved wrong.”

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