The stock market cautiously advanced yet again on Friday, and the S&P 500 Index (SNPINDEX:^GSPC) even finished at a new record closing high. If only all of its components could be so lucky: shares of Regeneron Pharmaceuticals (NASDAQ:REGN), Oracle Corporation (NYSE:ORCL), and Darden Restaurants, (NYSE:DRI) ended as the benchmark index's three worst stocks, each declining by more than 3%. The S&P, for its part, added 3 points, or 0.2%, to end at 1,962.

Regeneron Pharmaceuticals, a biotech company that largely hinges on the success of its macular degeneration product Eylea, plunged 4.2% on Friday. BMO Capital issued a note to investors saying that around 10% of Eylea users are switching to other treatments -- a spooky stat that, if true, would justify some caution on behalf of Regeneron shareholders. Unfortunately for investors, BMO's note, while hardly authoritative, is putting the market on edge simply because it could potentially be onto something.

Wall Street analysts also played a role in Oracle's 4% slump today, though this negative sentiment was mostly earned as a result of the tech giant's underwhelming quarterly report. Both earnings per share, or EPS, and overall sales in the most recent quarter failed to meet estimates: EPS came in at $0.92 against a $0.95 projection, and revenue came in at $11.3 billion versus calls for $11.5 billion. Sales of new software licenses also failed to impress Oracle investors, as they remained flat year-over-year.

Darden is thinking about selling its Red Lobster chain. Source: Darden Restaurants.

Finally, shares of Darden Restaurants, a restaurant operator that owns the Red Lobster, Olive Garden, and LongHorn Steakhouse brands, among others, lost 3.9% on Friday. Like Oracle, Darden Restaurants reported a bum quarter of sales and earnings, with Red Lobster and Olive Garden both losing revenue as earnings slipped 35% across the company. Its earnings per share projections for the current fiscal year also fell far below expectations, as the company forecast EPS between $2.22 and $2.30. Wall Street was hoping for EPS around $2.79. While investors can count their lucky stars that Darden's trying to dispose of its struggling Red Lobster franchise, the price tag probably took a hit today on the weak financial figures.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.