Bitcoin may have just bottomed, according to one investor.

The digital currency's unexpected surge on Tuesday caught Wall Street by surprise, spurring rumors of a deep-pocketed mystery buyer. Bitcoin prices climbed as much as 20 percent, trading above $5,000 for the first time since November.

Tuesday's moves were notable — bitcoin's best one-day gain since April 2018 — but one self-proclaimed bull wasn't too surprised.

"Sentiment has shifted here," Brian Kelly, founder and CEO of digital currency investment firm BKCM, told CNBC's "Futures Now" on Tuesday. "All indications that we have — whether it be fundamentals, technicals, the quantitative analysis we do — all suggest that we probably have at least started to put in the bottoming process."

Kelly, who also appears as a trader on CNBC's "Fast Money," pointed out that bitcoin's past trading cycles have looked "very similar" to its current pattern.

"You have that one last flush-out, and then the market starts to trade higher," he said. "What's interesting about this move is it's happening on improving fundamentals and improving institutional sentiment."

And while Tuesday's big buyer remains anonymous, more broad-based institutional interest is one of the main drivers for Kelly's bitcoin bull case.

"Even high net worth individuals, family offices, are starting to take a serious interest" in bitcoin, Kelly said. "There's a couple major brokerage firms that are rolling out some custody solutions. So there's quite a bid going on under the surface."

That bull case, which also hinges on increasing trading volume, improving fundamentals and an uptick in short sellers "covering," or cashing out of, their positions in bitcoin, could send bitcoin back to prices not seen since last November, Kelly said.

"Probably a reasonable target is close to $6,000 for this move," he said, noting that he wouldn't call bitcoin overvalued until it reached the $6,500 to $6,800 range.

Bitcoin prices traded in a wide range Tuesday, eventually stabilizing at roughly $4,700 a share, according to Bitstamp.