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

Dec. 6

Weekly Loss

ReneSola (SOL -2.25%)

$3.02

33%

J.C. Penney (JCPN.Q)

$8.08

21%

Titan Machinery (TITN 0.31%)

$15.01

16%

Nuverra Environmental (NESC)

$14.49

16%

Medallion Financial (MFIN 1.94%)

$15.99

10%

Source: Barron's.

Let's start with ReneSola. The solar-power bellwether lost a third of its value after posting disappointing quarterly results. That was the result of a one-time charge, but ReneSola still let investors down by posting uninspiring gross margins and offering up a gloomy outlook for the year ahead.

J.C. Penney proved mortal despite announcing its second consecutive month of positive same-store sales. The department-store chain was working on a 21-month streak of negative comps before that. However, J.C. Penney is still far away from where it was last holiday season, and things got worse later in the week, when the SEC began to inquire about its liquidity and financing.

Titan Machinery powered down after the retailer of agricultural and construction equipment delivered a horrendous quarterly report. Revenue was flat, but earnings fell nearly 60%. Titan clocked in short on both ends of the income statement. Its guidance was even worse, as Titan's new profit targets for fiscal 2014 are roughly half of what they were earlier this year.

Nuverra Environmental Solutions fell after executing a 1-for-10 reverse stock split. Exchanging 10 shares for a single share at 10 times the price is in theory a zero-sum game. However, the move often shakes out the speculators who were buying in as penny-stock gamblers. There have been a few reverse split success stories, but those are the exceptions instead of the rule.

Finally, we have Medallion Financial hailing a cab downtown. The company that offers financing for costly taxi license medallions stumbled after a dilutive secondary offering. Medallion Financial priced its 2.9 million freshly minted shares at $16.40, a steep discount to where the stock was the day before.