Donald Trump's presidency could drive monster gains in a particular corner of the stock market in the coming years, according to Fundstrat's head of research Tom Lee.

Speaking to CNBC on Friday, the permeable stock forecaster said he foresaw huge upside for small-cap stocks in the coming years. That's thanks to Donald Trump's recent election win, which sent stocks soaring this week as traders anticipated a fresh economic agenda, a looser regulatory environment, and lower taxes.

Small-cap stocks have done well so far this year, with the Russell 2000 up 18%. Still, the index of small-caps is trading at around 10 times forward median earnings, Lee noted, reflecting a lower valuation than the S&P 500, which is trading at around 17 times forward earnings.

"I do think there's still a lot of upside," Lee said. "So I think small-caps could, over the next couple of years, outperform by more than 100%," he added.

Lee, who previously predicted the small-cap Russell 2000 index could rally as much as 40% before the end of the year, also said he sees big gains ahead for other assets lumped into the Trump Trade, a handful of investments thought to benefit under the president-elect's policies.

Bitcoin, which notched a record-high this week, could climb past $100,000 by the end of the year, Lee predicted. The S&P 500, meanwhile, could rally another 5%-10% through year-end, he said, pointing to the size of previous post-election rallies.

"Part of the reason investors are feeling so optimistic is that President Trump is entering office again, but this time with a lot more knowledge of how to build a cabinet and a team, and so in some ways this end up being more market-friendly," he added.

Doubts, though, are swirling around some aspects of Trump's economic agenda, which experts have warned could stoke inflation and keep interest rates higher for longer. Trump's policies were thought to be more inflationary than Harris' by 70% of polled economists, according to a survey conducted by the Financial Times and the University of Chicago.