Many "meme stocks," which were aggressively promoted across social media platforms like Reddit, skyrocketed this year. Some of those stocks have solid fundamentals, while others -- like GameStop and AMC Entertainment Holdings -- are rallying entirely on hype and short squeezes.

It's tempting to chase those high-flying stocks, but it's smarter to tune out the noise and buy a few high-quality growth stocks that will continue rallying after the meme-stock rallies end. Magnite (MGNI -0.40%), Bumble (BMBL 0.74%), and Sea Limited (SE -2.22%) may be worth looking into.

Two children play with stacks of cash.

Image source: Getty Images.

1. Magnite

Magnite, the world's largest independent sell-side ad tech company, was formed by the merger of Rubicon Project and Telaria last April.

Magnite's sell-side platform (SSP) lets publishers and digital-media owners manage and sell their own ad inventories. It sits on the opposite end of the advertising supply chain from demand-side platforms (DSPs) like The Trade Desk, which lets advertisers and media buyers place bids on those ad inventories.

Digital advertising companies like Alphabet's Google provide both SSP and DSP services, but Magnite is a popular choice for publishers that want to sell their ads beyond Google's ecosystem.

Magnite serves ads on desktop and mobile platforms, but connected-TV devices represent its fastest-growing market. It recently acquired the video-advertising company SpotX to expand that business.

Magnite's revenue rose 42% to $221.6 million in 2020, while its adjusted earnings before interest, taxes, depreciation, and amortization (EBITDA) increased 68% to $43.1 million. Analysts expect its revenue to rise 79% this year as it integrates SpotX, then grow another 30% next year.

On the bottom line, they expect Magnite's adjusted earnings to more than triple this year and grow 42% next year. Those are astounding growth rates for a stock that trades at 37 times forward earnings and 10 times this year's sales. 

2. Bumble

Bumble, the online-dating company that lets female users make the first move on its main app, went public this February. It also owns Badoo, an older dating app that's popular in Europe and Latin America.

Bumble's revenue rose 19% last year, even as the pandemic throttled its growth in paying users, and its adjusted EBITDA rose 50%.

Bumble's growth accelerated as the pandemic passed. In the first quarter of 2021, its revenue jumped 43% year over year, adjusted EBITDA more than doubled, and the number of paying users increased 30% to 2.8 million -- which included 1.35 million Bumble users and 1.45 million Badoo users.

This year, Bumble expects its revenue to rise 34% to 35% and for adjusted EBITDA to grow 24% to 27% -- which are impressive growth rates for a stock that trades at 12 times this year's sales. By comparison, Tinder's parent company Match Group trades at 13 times this year's sales, but analysts only expect its revenue to rise 20% this year.

The critics often claim Bumble will struggle against Match's wider range of dating apps. But Bumble is also gradually expanding its own ecosystem -- with Bumble BFF for platonic friendships and Bumble Bizz for business connections -- and it hasn't even started monetizing those features yet.

3. Sea Limited

Sea is a Singapore-based e-commerce and gaming company. Its online marketplace, Shopee, is the e-commerce leader in Southeast Asia and Taiwan, and its Garena gaming division produces Free Fire, a battle-royale game that is incredibly popular in Southeast Asia and Latin America.

Sea's revenue soared 101% to $4.4 billion last year, with its e-commerce and digital-entertainment (gaming) revenue rising 160% and 78%, respectively. Analysts expect its revenue to rise another 90% this year. Sea's stock might seem pricey at 17 times this year's sales, but many other companies with slower growth trade at much higher price-to-sales ratios.

Sea is still unprofitable according to generally accepted accounting principles (GAAP), but it posted an adjusted EBITDA of $107 million last year, compared to a loss of $179 million in 2019.

Its adjusted EBITDA improved for two main reasons. First, Shopee narrowed its losses per order as it offered fewer promotions and subsidies. Second, Free Fire continued to gain paying users, which enabled Garena to generate a positive adjusted EBITDA and offset Shopee's losses.

That's a delicate balancing act, since Sea is essentially relying on a single hit game to support its unprofitable e-commerce platform. I believe, however, that both businesses could still have plenty of room to grow.