No matter the market, there will always be losers -- a few lagging disappointments holding back a Wall Street rally, or several big losers leading a bearish day. The S&P 500 (SNPINDEX:^GSPC) lost the momentum the markets have had recently as the index fell flat today. However, several big-name stocks took big losses and made investors pull their hair out in frustration. Facebook (NASDAQ:FB) notably took a big dive today, while Delta Airlines (NYSE:DAL) didn't fare much better. From tech to telecom, here are today's three worst losers on the S&P 500.

Delta drops back from sky-high gains
Delta slipped by 3% today after the company announced it will respect ultra-cheap ticket fares after a technical glitch led to some customers finding tickets for $50 or even less on the company's website. It's a temporary headache for Delta investors, but it's a good move for the company, and a welcome one for Delta's PR. Not honoring the ticket glitch could have resulted in serious customer backlash, and given how well Delta's soared this year -- the airline stock has more than doubled year to date -- the last thing the company needs is a spark to end its good run.

Rising oil prices didn't help Delta, or airlines in general today, as oil hit its highest mark since October, but fuel prices haven't hindered Delta's ascent this year. In fact, Delta's fuel and related tax expenses, its largest single category of operating expenses, fell more than 7% year over year through the first nine months of 2013. Delta has capitalized by gaining around 4.5% in mainline passenger revenue through that time, and it's paid off both on the company's financial statements and on the stock charts. Although the growing economy likely will push oil prices up further in the near future, the rising tide should also help boost passenger traffic and keep Delta's revenues -- and those of other major airlines-on the upswing.

Telecom firm Windstream Holdings (NASDAQ:WIN) didn't have much to offer investors today, either, as the stock lost more than 3.4% to end the week. Windstream's a favorite among dividend investors for its 12% dividend yield, but this stock's struggled despite the market's great year, losing around 4% since 2013 kicked off. While Windstream's kept its dividend payments on track through the year, the company has struggled through falling revenue in both consumer and wholesale services, outweighing the gains made by business service revenues. Still, Windstream's been among the more reliable dividend payers among the leading rural telecom providers in recent years, so while investors should keep a wary eye on the company's financials, there's no need to panic over this stock's performance so far.

Neither Windstream nor Delta matched up with Facebook's losses today, however, as the social media stock shed nearly 4%. Social media, in general, struggled through a tough day -- rival Twitter (NYSE:TWTR) plunged 13% to put a drastic halt to its recent run-up, a result of  a stock downgrade from Macquarie Capital. Facebook has also put on a nice show lately by more than doubling over the past six months, but a troubling report today threw cold water on the stock's momentum.

A European Union trial called the Global Social Media Impact Study discovered that Facebook use among 16 to 18 year-olds nosedived during the study's 15-month observation period. Youth, more and more, have turned to social apps such as Snapchat and WhatsApp, along with the likes of Twitter and Facebook's own Instagram. That doesn't mean it's time to worry for investors, however: Facebook's maturity has come with a better grip on advertising, and the study itself noted that children did acknowledge Facebook's technological prowess for organization and integration -- even if that didn't translate to usage. Facebook might not be as trendy with older teens as it used to be, but it's doing what it needs to do for the long term -- and for investors, that's the key for success.

Fool contributor Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends Facebook and Twitter. The Motley Fool owns shares of Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.