Wall Street took a downward turn Monday as federal tax reform during this session of Congress began to look more uncertain than ever. The S&P 500 and Dow Jones Industrials both fell about 0.4%, and investors struggled with concerns that the long-expected stock market correction could be sparked by any result that was less than a complete victory by the White House and the tax-cut wing of Republicans in Congress.

Adding to the downbeat mood were steep declines in the stocks of a few companies that suffered from bad news specific to them. Advanced Micro Devices (AMD -0.84%), Office Depot (ODP -0.04%), and Iconix Brand Group (ICON) 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.

AMD deals with detractors

Shares of Advanced Micro Devices dropped 11% after the chipmaker drew negative comments from various Wall Street analysts. Morgan Stanley cut its rating on AMD from equal weight to underweight, and cut its price target on the stock from $11 to $8  because of long-term doubts about whether temporary demand drivers like cryptocurrency mining and video game consoles will be able to offset the company's weaker performance in its core markets. Investors were already skeptical about the staying power of its recent surge, but today's move adds some credibility to the assertions, especially given the widespread high expectations among shareholders in AMD.

Box containing AMD Ryzen 7 chip, against an orange background that matches the color scheme of the box.

Image source: Advanced Micro Devices.

Office Depot deals with competition

Shares of Office Depot plunged nearly 20% on worries about its ability to grow in an increasingly competitive environment. The office supply retailer has long had to deal with competition from its archrival Staples, which will arguably have even greater capacity to fight for market share, assuming its plan to go private in the near future comes to fruition.

Now, e-commerce giants appear to be putting more effort into the office segment, which could further hurt Office Depot's prospects. Recognition of that trend led to negative comments from analysts at JPMorgan, who cut their rating on the stock from neutral to underweight, and said they expect less business for the company in the near future. Unless Office Depot can pull a rabbit out of its hat, the company's fundamentals appear increasingly bleak.

Iconix gets hammerd

Finally, shares of Iconix Brand Group took a more than 60% hit. The brand-management company  said that retail giant Wal-Mart (WMT -1.23%) had decided not to renew its license for the DanskinNow brand beyond January 2019. That will result in loss of about $15.5 million in royalty revenue for Iconix in 2018, which in turn raised the danger that it may violate its debt covenants with lenders. Iconix negotiated amendments to its credit agreements that will reduce the availability of a credit facility, and restructured some of its outstanding debt. Without Wal-Mart's business, Iconix will be under significantly heavier pressure to figure out a more effective strategy for making the most of its brand assets.