Amazon's stock will double in the next three years, noted investor Bill Miller told CNBC on Monday.
"Amazon's addressable market is so gigantic," said Miller, founder of Miller Value Partners and a longtime Amazon bull.
The tech giant, up 2.77 percent in afternoon trading, is now the most valuable public company in the world. It overtook Microsoft on Monday morning after reaching a market value of about $790 billion. Microsoft's market value stands at about $785 billion. In September, Amazon reached a $1 trillion market cap for the first time before losing ground in the late-year sell-off.
And while there has been a lot of talk about regulating tech companies, Miller is unconcerned about Amazon being broken up. For that to happen, antitrust laws would have to be changed and "they can't agree on anything in Congress. That's a long way off, if it happens," he said.
Meanwhile, Miller's fund, Miller Opportunity Trust, is "off to a very strong start this year," after having a "pretty bad" 2018.
He blamed last year's performance on the December rout, saying the sell-off "really, really hit us."
"At the end of the third quarter, I think we were about 700 or 800 basis points ahead of the market," he said. "We gave all that back and more in the fourth quarter."