The stock market continued to ascend on Tuesday, sending the Dow and S&P 500 up through new milestone levels. Stocks tend to perform fairly well near major U.S. holidays, and enthusiasm about the future prospects for the U.S. economy have outweighed any concerns about future uncertainty regarding the geopolitical and macroeconomic situation. Even with major market benchmarks gaining on the day, some stocks still fell, and Dycom Industries (DY -1.00%), CF Industries (CF 1.55%), and FireEye (MNDT) were among the worst performers on the day. Below, we'll look more closely at these stocks to tell you why they did so poorly.

Image source: Dycom Industries.

Dycom takes a dive

Dycom Industries plunged 20% after reporting its fiscal first-quarter financial results. The provider of specialty contracting services for corporate telecommunications and utility customers seemed to post fairly solid results, including a 21% rise in contract revenues and net income that climbed by two-thirds from year-ago levels. Yet investors reacted negatively to future-looking news, which included statements that one of its customers has "modified its plans" in such a way as to cut full-year revenue projections by $80 million and contract backlogs by more than $400 million. In addition, the company cut its outlook for one of its recently acquired units, leading to more than $200 million in backlog cuts. Those amounts add up to just over a tenth of the company's current backlog of just over $5.2 billion, but Dycom shareholders clearly worry that further deterioration could be lying in wait for the company in the near future.

CF wilts after a downgrade

CF Industries dropped 5% in the wake of getting a downgrade from analysts at RBC Capital Markets. The analyst company moved CF from sector perform to underperform, arguing that recent increases in prices for nitrogen-based fertilizers aren't likely to continue at their current pace, pointing to further capacity coming online in response to strong gains. If the commodity fertilizer markets don't cooperate, then CF Industries could see a direct hit to its earnings, thwarting those who had hoped that the long drought in the fertilizer industry might be coming to an end. For now, investors in CF can expect substantial volatility as market participants try to parse out the likely course of fertilizer prices over the next year or so.

FireEye looks less secure

Finally, FireEye fell more than 5%. The cybersecurity specialist got a negative assessment from analysts at Goldman Sachs, with comments that point to greater difficulty in capturing the huge opportunity in the space than investors currently believe. Moreover, despite the likelihood of consolidation in the cybersecurity industry, Goldman's analyst team isn't quite as optimistic as some other investors about the prospects for FireEye becoming an acquisition target. In response, the analyst moved the rating on the stock from neutral to sell, but with the caveat that if cyber-related attacks start to ramp up again and become larger in scope, FireEye could easily take advantage of increased demand for its services and have more success in getting contracts to cover major clients in the government and private sectors.