The top after-market Nasdaq gainers Monday were Digital Generation Inc, Codexis Inc, NuPathe Inc, Synacor Inc and Marten Transport Ltd.

The top after-market Nasdaq losers were Mattress Firm Holding Corp, Select Comfort Corporation, J.B. Hunt Transport Services Inc, ICU Medical Inc and FLIR Systems Inc.

Gainers

Digital Generation Inc (DGIT) shares climbed 21.85 percent to $11.71 in after-hours trading Monday. The company's shares surged after it announced Monday that it would review a number of strategic options, including partnership and sale. DG has engaged Goldman, Sachs and Co. to explore the strategic alternatives.

Shares of Codexis Inc (CDXS) rose 7.49 percent in the post-market to close at $4.16. The proprietary biocatalysts developer on Monday after market hours announced that it signed an Exclusive Negotiation Agreement with Shell, in which Shell has agreed to negotiate exclusively with Codexis for the grant of certain rights and licenses to develop and sell cellulase enzymes to third parties.

NuPathe Inc (PATH) shares advanced 8.99 percent to $4.00 in post-market trading. The company announced that it has resubmitted its New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for its migraine patch (NP101) and expects a six-month review from the FDA.

Synacor Inc (SYNC) shares gained 4.21 percent and reached $16.10 in after-hours trading. The company stocks slumped 4.28 percent in regular trade Monday.  

Marten Transport Ltd (MRTN) shares surged 3.27 percent to $19.04 in after-hours trading Monday. The shares of the company dropped 6.21 percent in regular trade Monday.  

Losers

Mattress Firm Holding Corp (MFRM) shares slumped 12.66 percent to $8.82 in the post-market Monday. The Houston-based Mattress Firm announced its revised forecast full-year sales to be between $1.01 billion and $1.03 billion from the earlier guidance of $1.03 billion to $1.06 billion.

Select Comfort Corporation (SCSS) shares plunged 7.36 percent to $21.40 in the post-market. The Commerce Department data showed that furniture sales fell 0.8% on the month, while the U.S. retail sales fell 0.5 percent month-over-month.

J.B. Hunt Transport Services Inc (JBHT) shares lost 3.65 percent in after-hours trading to reach $56.20. The company reported Q2 EPS of $0.67, in-line with the analyst estimate of $0.67. Revenue for the quarter came in at $1.26 billion against the analysts' expectation of $1.3 billion.

ICU Medical Inc (ICUI) shares dropped 2.52 percent to $50.36 in after-hours trading.  The company announced that based on the current business trends, it was narrowing the previously announced revenue guidance range for fiscal 2012. The new range is $318 million to $325 million, compared to the previous range of $318 million to $330 million.

FLIR Systems Inc (FLIR) shares declined 2.07 percent to $17.95 in after-hours trading. The company estimated its second quarter earnings to be below analysts' expectations, citing a weaker demand for its products from Europe.

The company expects adjusted earnings of 30 cents per share on revenue of $338 million versus analysts' expectation of earnings of 36 cents a share on the revenue of $380.1 million.