The top after-market Nasdaq gainers Tuesday were Riverbed Technology Inc, Ancestry.com Inc, BioCryst Pharmaceuticals Inc, Altera Corporation and iRobot Corporation Inc.

The top after-market Nasdaq losers were Netflix Inc, Buffalo Wild Wings Inc, TripAdvisor Inc, Amyris Inc and Horizon Technology Finance Corporation.

Gainers

Riverbed Technology Inc (RVBD) shares climbed 23.51 percent to $17.97 in after hours trading Tuesday. Network gear maker Riverbed on Tuesday gave a better-than-expected forecast for the third quarter. For the current quarter it expects earnings of 25 cents to 26 cents per share, on a revenue of $214 million to $219 million against the analysts' estimation of 24 cents per share, on the revenue of $209.7 million, according to a Reuters' poll.

The shares of Ancestry.com Inc (ACOM) rose 15.64 percent in the post-market to close at $31.49. The family-history research website is exploring a sale to private equity firms and is hoping to solicit revised bids from them in early August, Reuters reported on Tuesday, quoting two sources familiar with the matter.

BioCryst Pharmaceuticals Inc (BCRX) shares advanced 13.12 percent to $5.00 in the post market trading. The company announced favorable 52-week safety results and sustained efficacy from the extension phase of its randomized Phase 2b trial of ulodesine (BCX4208) added to allopurinol in patients with gout who had failed to reach the serum uric acid (sUA) therapeutic goal of <6 mg/dL on allopurinol alone, as well as positive Phase 2 safety results in patients with mild to moderate renal impairment.

Altera Corporation (ALTR) shares gained 9.23 percent and reached $33.50 in after hours trading. The company announceda second quarter revenue of $464.8 million, up 21 percent from the first quarter of 2012 and down 15 percent from the second quarter of 2011. The second quarter net income was $162.7 million, $0.50 per diluted share, compared with a net income of $115.8 million, $0.35 per diluted share, in the first quarter of 2012 and $214.6 million, $0.65 per diluted share, in the second quarter of 2011. Both the earnings and the net profit exceeded the analysts' expectation.

iRobot Corporation (IRBT) shares surged 1.42 percent to $2.85 in after-hours trading Tuesday. The company reported 29 cents per share for the quarter, beating the analysts' consensus estimate of 9 cents per share. iRobot's revenue was up 3.1 percent compared to the same quarter last year.

Losers

Netflix Inc (NFLX) shares slumped 16.66 percent to $13.30 in the post market trading Tuesday. The company said it may have trouble reaching its year-end target for new subscribers. The company said it expects to be profitable in the third quarter, but may report a consolidated loss in its fourth quarter because of its next international market launch.

Buffalo Wild Wings Inc (BWLD) shares plunged 15.53 percent to $12.25 in the post market trading. The company reported a second quarter EPS of $0.62, worse than the analyst estimate of $0.68. Revenue for the quarter came in at $238.7 million versus the analysts' estimate of $240.23 million.

TripAdvisor Inc (TRIP) shares lost 14.88 percent in after-hours trading to reach $37.0. The company reported second quarter EPS of 41 cents, which met the analysts' estimate but the revenue for the quarter came in at $197.1 million versus the consensus estimate of $202.47 million.

Amyris Inc (AMRS) shares dropped 10.03 percent to $3.14 in after-hours trading. The company shares have a 52-week low of $1.57, a 52-week high of $25.77 and $196.55 million in market capitalization.

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