Last Week's Biggest Movers on Wall Street

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.

Energy Recovery (ERII) -- Up 200 percent last week

The market's biggest winner was Energy Recovery, tripling in value after striking a lucrative 15-year licensing deal with Schlumberger (SLB). Schlumberger will have exclusive rights to Energy Recovery's VorTeq hydraulic pumping system.

The deal calls for Energy Recovery to receive $125 million as well as ongoing royalties for the rights. That's a pretty big deal for Energy Recovery, as that was roughly the stock's market cap when the week began.

Weight Watchers (WTW) -- Up 132 percent last week

%VIRTUAL-WSSCourseInline-1003%Oprah Winfrey came to the rescue of one of this year's worst performers. Winfrey revealed that she will be taking a 10 percent stake in the diet plan specialist. She will also be taking an active role in promoting the brand, something that is ultimately more important than taking a minority stake in the company. Winfrey's influence is obvious and she can certainly help a brand that really needs it.

Revenue has been sliding at the company. Folks pay an average of $377 a year to Weight Watchers, and that's hard to justify in a world where fitness apps and websites offer cheaper ways to encourage active lifestyles and healthy eating. If anyone can help turn things around, it's probably Winfrey.

Higher One (ONE) -- Up 33 percent last week

An asset sale helped push shares of Higher One higher. It agreed to sell its Campus Labs data analytics business in a $91 million deal. Higher One has fallen out of favor since its days as a market darling when it revolutionized personal finance on college campuses. Unloading a subsidiary isn't going to help its overall business, but unlocking the value always helps.

Pandora Media (P) -- Down 38 percent last week

The market turned down the volume on Pandora after the streaming music pioneer posted a problematic quarterly report. Usage is slipping. There may be a whopping 78.1 million active listeners relying on Pandora for music, but that's below the 79.4 million active listeners that it had on its rolls just three months earlier. The number of hours of content served also slipped sequentially to 5.14 billion from 5.3 billion.

The launch of Apple's (AAPL) new premium streaming service at the start of the quarter clearly didn't help. Apple Music was offering three free months to get folks to use its service and it appears to have initially won over some Pandora users. The real test will come in the current quarter as Pandora tries to woo those music fans back.

Skechers (SKX) -- Down 30 percent last week

Another stock that got tripped up on loose laces was Skechers. It posted quarterly results that fell short of Wall Street forecasts. Revenue clocked in at $856 million. Analysts were holding out for $877 million.

Domestic wholesale sales rose at a mere 12 percent clip over the prior year. Double-digit growth isn't a problem, but Skechers was growing a lot faster in its previous quarters.

Apollo Education Group (APOL) -- Down 28 percent last week

Finally, we have the parent company of the University of Phoenix flunking out. Apollo posted a 14 percent year-over-year drop in revenue, fueled by yet another decline in enrollment levels. There are 190,700 degreed enrolled students at Apollo's schools, but that's a sharp drop from the 233,500 folks that it was schooling a year earlier.

Motley Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Apple, Pandora Media and Skechers. 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.