The world's best-performing mutual fund features Juul Labs as its top holding. Here are its 12 other biggest bets.

• The Fidelity Advisor Growth Opportunities Fund is beating out the rest of its mutual fund peers over the past 12 months, according to Kiplinger, returning 27%.
• Juul Labs, the private e-cigarette maker, is the fund's top holding. Markets Insider has compiled some of the fund's other largest positions here to show what else the high-flying fund is betting on.
• Watch some of the fund's other top holdings, like Alphabet, Amazon, and Apple, trade in real-time.

The largest holding in the top-performing large stock mutual fund isn't a publicly traded stock at all.

The Fidelity Advisor Growth Opportunities Fund is beating out the rest of its peers over the course of the last year, returning 27% in that time, according to Kiplinger data.

And it's betting on some widely held names that might not surprise investors: mammoths like Apple, Amazon, and Facebook that Wall Street is generally quite bullish on.

But its largest bet is on an entirely different animal. Juul Labs, the e-cigarette startup valued at $38 billion last December, comprises 5.3% of the Fidelity fund, according to its latest filing.

Juul Labs gained attention in December after tobacco giant Altria paid $12.8 billion for a 35% stake in the company, sparking a renewed discussion over the future of the fast-growing e-cigarette industry.

Altria, which makes Marlboro cigarettes, said earlier this year that Juul Labs recorded $1 billion in revenue in 2018, up from $200 million a year earlier. Since Juul is a private company, investors can't look at its financials in the same way they can a public one.

Its weighting in the high-performing Fidelity fund is slightly larger than the next few main holdings - Alphabet's Class C shares (4.8%) followed by Microsoft and Amazon shares (both at 4.6%), and Amazon shares (3.9%).

Kyle Weaver, the portfolio manager overseeing the fund, said in its annual report last November that stock-picking in the consumer staples sector stood out. That included "top contributor" Juul Labs.

"Sales of the company's e-cigarette devices and pods increased significantly the past 12 months, leading to a higher valuation," Weaver said.

Still, he added: "The company and the industry face a number of social and public policy concerns."

Read more: The FDA commissioner just launched a crackdown on e-cigs like Juul as he prepares to leave office

Other classes of Juul Labs stock are included in the fund as well, but at far smaller weightings. As of the fund's latest monthly report, on January 31, it contained 208 components.

Here's a snapshot of the fund's top holdings, along with their performance in the year through January 31, 2019 - when Fidelity last detailed the fund's positions in its monthly holdings report.