There's never a shortage of losers in the stock market.

Let's take a closer look at five of this past week's biggest sinkers.

Company

Nov. 9

Weekly Loss

My Watchlist

James River Coal (NASDAQOTH:JRCCQ)

$2.70

(40%)

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Molycorp (NYSE:MCP)

$7.50

(24%)

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VIVUS (NASDAQ:VVUS)

$10.84

(24%)

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Universal Display (NASDAQ:OLED)

$24.41

(22%)

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NII Holdings (NASDAQ:NIHD)

$6.13

(21%)

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Source: Barron's.

Coal miners took a hit after President Obama was reelected, and James River Coal suffered the most. Coal producers were already hurting, and James River Coal is in a very challenging financial position these days.

Molycorp posted healthy growth in its latest quarter, but the rare-earth minerals specialist fell to Earth after revealing a formal SEC investigation into the company's public disclosures.

VIVUS is off to a bad start with its anti-obesity drug. In its first quarter since Qsymia has been made available, revenue barely topped $40,000. Analysts were expecting revenue of roughly $300,000. The treatment was only available during the last 10 days of the month, but it's still a disappointing figure. There are also concerns that those who are getting prescriptions for Qsymia are balking at the price and not getting those orders filled.

Universal Display took a hit after the OLED pioneer posted weak revenue growth, surprised investors with a loss when they were expecting a small quarterly profit, and hosed down its revenue guidance for the year.

NII Holdings hung up on investors after the wireless carrier offering the Nextel brand in Brazil offered up disappointing quarterly results. NII's substantial decline in mobile phone accounts there also didn't help.

Longtime Fool contributor Rick Aristotle Munarriz has no positions in the stocks mentioned above. The Motley Fool owns shares of Universal Display. Motley Fool newsletter services recommend Universal Display . 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.