Wall Street had its Cinco de Mayo celebration a day early, as the Dow Jones Industrial Average finished the session with a gain of more than 330 points. Investors were excited about what they saw as a Goldilocks-like reading on the U.S. economy in the April employment report, which featured modest job growth, rock-bottom unemployment rates, and slow enough wage growth to quell inflation fears and give the Federal Reserve latitude to raise interest rates more slowly going forward. Yet some companies still suffered at least perceived setbacks that sent their shares lower. Fluor (FLR 1.63%), Arista Networks (ANET 3.53%), and Appian (APPN -1.02%) were among the worst performers on the day. Here's why they did so poorly.

Fluor gets a nasty surprise

Shares of Fluor plunged more than 22% after the engineering and construction company reported its first-quarter financial results. Investors had expected solid profits from the company, but Fluor said that it had to take an after-tax charge of nearly $100 million because of the need to revise forecasts about costs of a gas-fired power project. That cost the company almost $0.70 per share in earnings, and the $1-per-share cut to the company's full-year 2018 guidance suggests that Fluor expects more pain from the project in the future. Fluor hopes that new projects from a recovering energy sector will help it grow, but the hit was immensely disappointing for the company and its shareholders.

Fluor logo.

Image source: Fluor.

Arista tumbles on feared slowdown

Arista Networks stock fell 8.5% in the wake of the company's first-quarter financial report. The networking hardware specialist reported strong growth, including a 41% rise in revenue and a huge 87% jump in adjusted earnings. Yet traders seemed to react to guidance that Arista sees roughly 25% growth coming in the current quarter, and the idea that the company's top-line gains could slow so abruptly was jarring. Those who've owned the stock longer know that Arista has often been able to outdo its conservative guidance, and with demand for network improvements still strong throughout the industry, today's decline could really be a blessing in disguise for those looking to buy shares more cheaply.

Appian keeps growing, but investors are still scared

Finally, shares of Appian dropped 9%. That might come as a surprise given that the low-code software development platform provider reported strong quarterly sales results for the first quarter, seeing growth of 35% overall. Gains of 36% in subscription-based revenue and 46% in professional services revenue helped power the company forward, and retention rates continued to signal not only customer loyalty but also a willingness to buy more services over time. Yet as we saw with Arista, some investors didn't seem happy with wider losses and future growth estimates, even though Appian boosted its guidance for the full year. By solving a key need for enterprise clients, Appian thinks it can grow faster for a lot longer than short-term-minded traders are giving it credit for.