Major benchmarks got off to a gloomy start on Monday, as investors weren't able to sustain the upward momentum that sent popular indexes to new records last week. As the year draws to a close, many market participants are considering just how successful the 2010s have been for stocks, pointing to standout companies. Yet a few stocks still lost significant amounts of ground. International Flavors & Fragrances (NYSE:IFF), Precision BioSciences (NASDAQ:DTIL), and GameStop (NYSE:GME) were among the worst performers. Here's why they did so poorly.

IF&F gets into a flavor fight

Shares of International Flavors & Fragrances sank 6% on reports that the company is looking to purchase the nutrition business of DuPont (NYSE: DD). Unfortunately, there's a potential competing bidder in Irish food producer Kerry Group, and it's uncertain what the outcome of a bidding war might be. Purchasing DuPont's nutrition business would be a strategic victory for IF&F, largely because it would broaden the combined company's scope and open up new opportunities in the food business. However, paying too much for the unit would be a mistake, and so shareholders won't be certain what the outcome will be until the process plays itself out.

Person wearing purple gloves holding bottle and a tester.

Image source: International Flavors & Fragrances.

Precision BioSciences takes a hit

Pharmaceutical company Precision BioSciences saw its stock lose more than half its value after it released preliminary data from a phase 1 trial of its non-Hodgkin lymphoma and leukemia treatment, PBCAR0191. Precision was "very encouraged by the evidence of cell-mediated anti-tumor activity and objective tumor responses," according to Chief Medical Officer Chris Heery, and the company is hopeful that the study will keep producing good results. Investors weren't entirely happy with all of the data, but it's important to understand that the stock had soared in recent weeks. Even with today's drop, Precision shares are still up by almost half in less than six weeks.

GameStop sustains damage

Finally, shares of GameStop fell 5%. The video game retailer is set to release its quarterly results on Tuesday, and investors anticipate that the company's sales and net income are likely to be significantly lower than they were during the year-earlier period. Recent quarters have featured double-digit percentage declines in comparable-store sales, reflecting the difficulty that GameStop has had wooing customers into its physical store locations. As more video game sales move online, it could prove increasingly difficult for GameStop to sustain its business model in its current form, and shareholders are trying to come to grips with that reality.