If you're a fan of bargain stocks, there's certainly no shortage of beaten-down tickers right now. Even a handful of familiar stalwarts that help make up the S&P 500 (^GSPC 0.12%) have been more than halved just since the beginning of the year, inviting investors to take a swing while they're down.

Before going on a buying spree while certain stocks are seemingly cheap, though, you might want to take a step back to look at -- and think about -- the bigger picture. This extreme weakness of some large-cap names might be as much a warning as it is an opportunity.

What went wrong

For the record, the worst of the worst S&P 500 names so far this year are Match Group (MTCH -0.48%), Align Technology (ALGN -0.75%), and Netflix (NFLX 1.73%), down 56%, 62%, and 63%, respectively, since the end of 2021. Those are deep discounts by anybody's standards.

A deep discount, however, doesn't inherently mean a stock is worth scooping up.

Take Align Technology as an example. The company behind Invisalign dental braces is undeniably working a brilliant idea -- straighter teeth are always marketable. Clear braces themselves, however, aren't proving as persistently or increasingly marketable as they were once believed to be. The company's second-quarter top and bottom lines not only fell short of estimates but also fell on a year-over-year basis.

While currency headwinds and lingering COVID-19 restrictions are partly to blame, Align still somehow mustered a sales surge throughout 2021 despite the pandemic that's clearly fading now. It could well be a sign that demand for this sort of service is already plateauing.

Analysts don't necessarily agree with that prospect, modeling top-line growth of more than 12% next year, nearly restoring the record-breaking earnings results achieved last year as a result. Given the backdrop behind this year's clear slowdown, though, that's understandably not a bet many investors are willing to make.

The root of Netflix's rout is even clearer. For the first time in its modern history, the company lost streaming subscribers during the first quarter of the year and followed that tough quarter with even greater subscriber attrition during the second quarter. Russia's invasion of Ukraine deserves a portion of the blame. By and large, though, that slowdown signals that the streaming market is not only crowded with competition but that consumers themselves are also willing to try alternatives, canceling their Netflix service in the process.

As for Match Group, the suite of dating websites saw its business continue to grow into, through, and even out of the throes of the pandemic. The future, however, isn't looking nearly as bright as the recent past has been. Not only was its second-quarter bottom line shy of estimates, its revenue forecast for the current quarter also came up short of expectations. Word that the CEO of its Tinder unit, Renate Nyborg, was stepping down only added to the worries for current and prospective shareholders.

More than mere short-term headwinds

At first blush, these steep sell-offs could be chalked up to bad luck and unfortunate timing. And perhaps that's all it is.

But take a step back and look at the bigger picture. In all three cases, these stocks' struggles arguably reflect deeper, more philosophical challenges that won't be easily shrugged off.

Take Netflix, for example. It's no coincidence its subscriber growth slowdown is taking shape shortly after the launch of Warner Bros. Discovery's HBO Max and Walt Disney's Disney+. With advertising data-analyst Kantar's estimate that the average U.S. household now uses 4.7 streaming services (with the rest of the world not too far behind), there's not a lot of room or reason to expect more penetration. Netflix's planned ad-supported version will help, but the ad-supported streaming arena is rather crowded as well. Given that the company has few other revenue levers to pull, there's good reason for investors to be wary of Netflix.

Align Technology and Match Group are apt to be waist deep -- for the first time ever -- in comparable philosophical challenges. The younger digital-native crowd that first embraced apps like Tinder are now embracing the even more offbeat (and obscure) dating apps like Snack and Meet Lolly.

Meanwhile, straight teeth may never go out of style, but consumers have more teeth-straightening options than ever. The cost of professional fittings from authorized Align Technology orthodontists can be comparable to the cost of traditional braces, driving prospective customers to seek out alternatives. And in the past decade, a slew of competitors like SmileDirectClub and Byte have popped up on the market offering DIY treatments with the convenience of aligners sent directly to customers' homes, virtual check-ups, and more affordable prices.

More questions than answers? Take the hint.

None of this is to suggest shares of Align Technology, Match Group, or Netflix won't be higher a year from now, or even a few weeks from now. They could well be. But sometimes the world changes more than a company's business plan can adequately adapt to. That's likely what is happening here with these three tickers. There are still far too many questions and too few answers for each company.

A big sell-off isn't enough of a reason to step into a stock no matter how well known or reputable the underlying company may be. Owning stocks is always a case-by-case affair that requires a quality product and a growth model with true longevity.