Thursday was another sluggish day on Wall Street, with the Dow once again moving away from the 20,000 mark rather than toward it. Most major market benchmarks were down slightly on the day, as investors seemed content to coast into the end of the year as they wait to see whether things in 2017 will go as well as the recent stock market rally would suggest.

Yet even though trading activity was generally light, some stocks still gave up considerable amounts of ground, and Cliffs Natural Resources (NYSE:CLF), Groupon (NASDAQ:GRPN), and Alnylam Pharmaceuticals (NASDAQ:ALNY) 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: Cliffs Natural Resources.

Cliffs eases lower

Cliffs Natural Resources dropped 4% on the day, continuing to give back some of its gains since the presidential election in November. The producer of iron ore soared last month, climbing almost 60% on hopes that a promised boom in infrastructure spending would lead to greater demand for steel, in turn boosting its prospects in supplying raw materials for steel production to manufacturers.

Yet after climbing another $2 per share early in the month, Cliffs has now given back all of its December gains, with shareholders steadily watching the stock price fall as doubts about the staying power of government stimulus have started to creep into investors' collective consciousness. Even with the declines, however, Cliffs still trades at more than five times its worst level of the year, highlighting the extent of the commodities recovery in 2016.

Groupon doesn't look like a deal

Groupon fell 5%, dropping to its lowest levels since July as the online daily deal and internet retailer failed to impress investors with how its holiday season has been going. In an extremely competitive retail environment, it's hard for the corporate customers that Groupon relies on to do deals to afford the sorts of promotional discounts that are necessary to mount successful Groupon campaigns.

At the same time, Groupon has doubled down on the space, with its announced acquisition of rival LivingSocial eliminating its primary competitor, but leaving it fully exposed to the health of the industry. Still, between the daily deals space and its efforts to make direct sales through its online marketplace, Groupon still has to figure out a strategic vision for the long run, and investors seem skeptical that the company will do so successfully.

Alnylam eases lower

Finally, Alnylam Pharmaceuticals declined 5%. The biotechnology industry generally had a sluggish day in the stock market, with biotech sector ETFs moving slightly lower and continuing to go through a tough year. Yet for Alnylam, company-specific concerns appear to be playing a role, with the stock down by a quarter since its mid-November peak.

Investors were excited when Alnylam coaxed Sanofi into working together toward developing and commercializing hemophilia treatment fitusiran. However, since then, investors have appeared to return to a less optimistic view of the stock, pointing to its October decision to discontinue development of key amyloidosis candidate drug revusiran. Alnylam will have to make good on its promise to reinvigorate its pipeline in 2017 if it wants to convince shareholders that a true rebound is sustainable.