Week's Winners, Losers: Walmart's Gains, 3-D Printing's Pains

There were plenty of winners and losers this week, with America's leading online retailer calling a truce with a major book publisher and a solar panel installer letting the market down in its first quarter as a public company. Here's a rundown of the week's smartest moves and biggest blunders.

3-D Printing -- Loser

It was another rough week for 3-D printing. 3D Systems (DDD) kicked things off by reporting quarterly results on Monday. The 3-D printing pioneer saw its adjusted earnings plunge 25 percent. Sales grew, but growth has decelerated significantly.

Smaller rival ExOne (XONE) followed two days later with its own disappointing report. ExOne posted a much wider loss than analysts were expecting, and it also offered up uninspiring guidance.

Walmart (WMT) -- Winner

The world's largest retailer is showing signs of life. Walmart posted encouraging quarterly results on Thursday. Comparable-store sales for its domestic stores increased 0.5 percent. It may not seem like much -- and store traffic itself was negative -- but it's Walmart's first positive comps in nearly two years.

You have to go back to 2012 to find the last time that Walmart posted positive comparable-store sales. Its Neighborhood Market format saw an even more robust 5.5 percent spike in comps.

Vivint Solar (VSLR) -- Loser

The cardinal rule with every initial public offering is that you don't disappoint investors in your first quarter as a public company. You don't make your exchange debut until you're sure that you can deliver strong results. If you let the market down out of the gate, it will take several quarters -- if not years -- to regain the trust of investors. Wall Street winds up assuming that you went public as an exit strategy or a way to raise some quick cash. Well, apparently Vivint Solar didn't get the memo.

The installer of residential leased solar rooftop panels took a hit on Tuesday after posting a wider loss than analysts were targeting. Vivint Solar's adjusted deficit of 66 cents a share was more than three times the red ink that Wall Street pros were modeling. The stock was already trading below September's IPO price of $16 before the disappointing report. It's naturally trading even lower now.

Amazon.com (AMZN) and Hachette -- Winners

The long-standing dispute between Amazon and Hachette has ended. Amazon was blocking sales of Hachette-published books during the disagreement. Hachette will now be able to set e-book prices, but the terms of the deal are not being made public.

Hachette Book Group may not be out of the woods just yet, though. There are rumblings that authors aren't happy with collecting just 25 percent of their e-book sales. However, it's still good to see Amazon and a leading publisher play nice.

Calvin Klein -- Loser

Fashion designers surround themselves with razor-thin models. There's nothing inherently wrong with that, but it could be a problem when they appeal for the mass market. Calvin Klein took some flak this week for promoting a line of plus-size lingerie with a model who wears a size 10.

Social media turned on Calvin Klein for the move. Hiring model Myla Dalbesio for the lingerie shoot could have been a smart move if she hadn't been billed as a plus-size model. She is larger than the typical Calvin Klein model, but she's not going to help with the negative body images that the fashion industry is often accused of promoting. Some sources say that Dalbesio's closer to a size 8, New York Magazine reports.

Motley Fool contributor Rick Munarriz has no position in any stocks mentioned. The Motley Fool recommends and owns shares of 3D Systems, Amazon.com, and ExOne. Try any of our Foolish newsletter services free for 30 days. Check out our free report on the Apple Watch to learn where the real money is to be made for early investors.