Last Week's Biggest Stock Movers

Plenty of stocks go up and down in any given week. The gainers inspire us to keep investing. The decliners keep greed in check while reminding us about the risks of the equity markets.

Let's go over some of last week's best and worst performers.

Inotek Pharmaceuticals (ITEK) -- Up 246 percent last week

The market's biggest winner was Inotek, which saw its stock more than triple after announcing favorable phase 2 clinical trials for its promising glaucoma drug. Inotek laid out its strategy in tackling the third and final phase of the approval process.

At least one Wall Street pro is buying into the story. Cowen & Co.'s Ken Cacciatore bumped his price target on the shares to $40 from $15. This is a pretty big move for a stock that hadn't done much since going public five months ago.

Pandora Media (P) -- Up 14 percent last week

%VIRTUAL-WSSCourseInline-935%A better-than-expected quarterly report sent shares of Pandora higher. Revenue rose 30 percent since the prior year, just ahead of the streaming music provider's guidance. Its adjusted profit of 5 cents a share was more than double what analysts were forecasting.

It's a strong quarter for Pandora and it comes at a great time. Competition has been heating up in digital music, with Spotify gaining ground and Apple Music relaunching. Pandora is proving that it can do more than merely hold its ground.

Ambarella (AMBA) -- Up 12 percent last week

Another big winner was Ambarella, gaining ground after wearable camera maker GoPro (GPRO) came through with a blowout report Tuesday. Ambarella provides the video chips used by GoPro and Wall Street made the connection.

Canaccord Genuity raised its estimates on Ambarella following GoPro's encouraging report. It also boosted its price target to $122 from $120, pointing out that Ambarella's differentiated processors give it a significant lead in a historically cutthroat niche. It also sees strong potential in the drone market. GoPro itself moved 10 percent higher on the week, but Ambarella was the one with the bigger pop.

Xoma (XOMA) -- Down 79 percent last week

The market's biggest winner may have been a biotech, and the same can be said of its biggest loser. Xoma shed nearly four-fifths of its value after a doomed clinical trial.

Xoma had high hopes for gevokizumab, a potential treatment for eye symptoms associated with the rare Behcet's disease that results in the inflammation of blood vessels. A late-stage trial of the treatment failed to meet the study's primary endpoint. Xoma tried to offset the devastating news by pointing out that it noted preserved visual acuity, less severe ocular exacerbations and a reduced incidence of reported macular edema, but ultimately it failed to meet its main objective.

There was a lot riding on the drug, and that's now obvious given the market's reaction to the clinical trial's failure.

TrueCar (TRUE) -- Down 38 percent last week

Shares of TrueCar plunged into the single digits after posting preliminary quarterly results that proved problematic. TrueCar provides haggle-free pricing on cars, arming consumers with the average price paid on desired vehicles through a growing number of participating dealers.

TrueCar is lowering its guidance for all of 2015, and while the low end of its new revenue forecast calls for top-line growth of at least 21 percent, it suggests that revenue for the second half of the year will slow to 14 percent. It's not the trend that investors like to see, leading the market to wonder if auto sales in general are slowing or if it's TrueCar's own platform that's struggling.

Angie's List (ANGI) -- Down 32 percent last week

Angie's List slipped after posting quarterly results. The subscription-based website that offers vetted reviews of local service providers posted a quarterly loss on lower-than-expected revenue. That's worrisome to investors because they were already fretting about Angie's List's viability in a world where social media and crowd-sourced review sites offer guidance for free.

Motley Fool contributor Rick Munarriz owns shares of Ambarella. The Motley Fool recommends Ambarella, GoPro, Pandora Media and TrueCar. The Motley Fool owns shares of Ambarella, GoPro and Pandora Media. Try any of our Foolish newsletter services free for 30 days. Check out our free report on one great stock to buy for 2015 and beyond.