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) ended the day up a fraction of a percent, but several notable big names helped to weigh down the index, and make investors pull their hair out in frustration. Here are the three worst stocks today that you need to know about – from retail to health care, these stocks put a dent in Wall Street's Thursday.

Shareholders in full retreat
Kicking off our list of today's sinking stocks, Mondelez (NASDAQ:MDLZ) didn't treat shareholders to a good day, with shares shedding 4.3%. The former Kraft Foods took the market's latest hit from earnings season, whiffing on both the top and bottom lines  for the fourth quarter. Earnings per share fell from $0.47 a year ago to $0.30, while revenue dipped nearly 2% year over year to $9.5 billion.

Like many companies spread out across the world, Mondelez took a hit from currency issues due to the strong dollar; Europe particularly whacked the company, with revenue from the continent falling more than 7%. However, Mondelez did increase its 2013 outlook for earnings, and the company's sales growth in emerging markets is a promising sign. Today was a tough day for shareholders, but Mondelez doesn't look to be in any real danger of falling into a slump.

The future's not so bright over at health-care firm Hospira (NYSE:HSP). The maker of medical devices, biosimilars, and more, took a beating today, as shares plummeted nearly 8%. The culprit? Thank the FDA for this one: Hospira announced in an SEC filing that the FDA expanded an import ban  on three intravenous pumps made in the company's Costa Rica plant. That decision spurred Hospira to retract its 2013 guidance from Wednesday's earnings report, noting that revenue could  fall by $50 million to $100 million, and earnings could slide from $0.05 to $0.15 per share. Ouch.

Hospira's pain is a tough blow to shareholders, but one stock's dip today could indicate a great buying opportunity.

Whole Foods (NASDAQ:WFM) was slammed today, after shares fell 9.7%. The company updated its 2013 guidance, expecting revenue to grow by between 10% and 11%, after earlier predicting growth  of between 10% and 12%. Analysts expected higher revenue growth, although the difference between Whole Foods' expectations -- around $12.87 billion to $12.99 billion in sales -- and analyst projections of $13.2 billion, is minimal.

Naturally, investors reacted to that tiny revision by losing their minds, and exploding in a sell-off. The stock had pulled in gains of more than 8.6% over the past month until today, and Whole Foods has soared beyond expectations in the recent past. My advice? Don't follow the herd; pick up more of this rock-solid stock on the dip. Long-term investors have no need to fret about the minor revision to revenue guidance.

Fool contributor Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends Whole Foods Market. The Motley Fool owns shares of Whole Foods Market. 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.