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

Sept. 27

Weekly Loss

J.C. Penney (JCPN.Q)

$9.05

30%

Cypress Semiconductor (CY)

$9.05

21%

Arch Coal (NYSE: ACI)

$4.25

10%

Westport Innovations (WPRT 9.10%)

$24.83

10%

Himax (HIMX 0.97%)

$9.72

10%

Source: Barron's.

Let's start with J.C. Penney. The struggling department-store chain lost nearly a third of its value during a brutal week that saw it resorting to a secondary stock offering to raise funds. J.C. Penney's burning through money as it tries to stage a turnaround, and the concern before the financing was that suppliers would hold back on delivering goods to the troubled chain. However, offering a secondary offering -- at a discount -- when the stock's at a multi-year low isn't going to win many fans.

Cypress Semiconductor tumbled after hosing down its guidance for the current quarter. Experiencing greater-than-expected weakness in its mobile-handset revenue, Cypress now sees a profit of $0.10 to $0.12 a share on revenue of $184 million to $187 million. Its earlier guidance was calling for at least $0.17 in earnings and for revenue to top $200 million.

Arch Coal was a lump of coal after a Goldman Sachs downgrade. Arch's heavily leveraged balance sheet, low coal prices, and potential plant retirements find the firm lowering its rating from "neutral" to "sell." The stock's price target is going from $4 to $3.

Westport Innovations slipped after completing a secondary stock offering. The provider of natural gas fueling solutions priced 6 million shares at $25.39 on Thursday, a big discount to the stock's close at $27.30 on Wednesday. It's good to see Westport pick up roughly $175 million in financing, but the offering is dilutive, and the discount isn't going to make existing shareholders feel any better.  

Finally, we have Himax taking a step back. There was no material news out on Himax, but the maker of display chips had moved 22% higher a week earlier after receiving an analyst upgrade. Chardan Capital Markets analyst Jay Srivatsa boosted his price target on the shares to $12, seeing a boost in Himax's micro-displays in wearable computing devices.