This week has proven to be a disappointment for bullish investors who were hoping to see the Dow Jones Industrials reach a historic 20,000 milestone. Friday brought slight gains to the overall stock market, but they weren't enough to push the Dow into uncharted territory, and advances for most major market benchmarks were limited to less than a quarter of one percent.

Investors have high hopes for 2017, but they appear reluctant to try to get a head start on New Year's celebrations, despite the potential for thin holiday trading to produce extreme volatility. Still, some stocks posted sizable gains, and Portola Pharmaceuticals (NASDAQ:PTLA), Caesars Entertainment (NASDAQ:CZR), and Cal-Maine Foods (NASDAQ:CALM) were among the best performers Friday.

Below, we'll look more closely at these stocks to tell you why they did so well.

Image source: Caesars.

Portola posts a key FDA win

Portola Pharmaceuticals jumped more than 35% after the small biopharmaceutical company said that it had received a favorable ruling from the U.S. Food and Drug Administration. Portola won FDA priority review of its application for the company's betrixaban oral treatment for sufferers of venous thromboembolisms. The granting of priority review will shorten the future review timeline by the regulatory agency from 10 months to six months, and as a result, Portola expects FDA action on the drug by June 2017.

Portola also took the opportunity to announce that the European Medicines Agency had validated its marketing authorization application for betrixaban, with a standard review period on the Continent. Portola CEO Bill Lis said that the company now looks forward to bringing the drug to market after gaining final approval from the two agencies, but that process still involves some uncertainty, despite substantial promise for the drug.

Caesars hopes for a winning bet

Caesars Entertainment climbed 9% in the wake of news that the company's bankrupt subsidiary had reached agreement with some of its creditors to accept new terms under its bankruptcy plan. Investors had been nervous that any change in the plan for Caesars Entertainment Operating Company might result in the Caesars parent company having to provide additional capital in order to satisfy lenders; the companies had hoped to be able to restructure in accordance with the plan in a way that would prevent any such risk.

If the agreement leads to a final path forward, then Caesars might finally be able to put the episode behind it, and focus on taking advantage of opportunities in the casino industry.

Cal-Maine climbs despite weak sales

Finally, Cal-Maine Foods gained 7%. The egg producer reported its fiscal second-quarter results Thursday afternoon, and it saw sales slide by more than half as huge declines in egg prices weighed on the company's ability to perform well. The company lost $1.12 per share, compared to year-ago profits of $5.22 per share during a time when industry fundamentals were much stronger.

Oversupply in the market continues to be a problem, but Cal-Maine CEO Dolph Baker still thinks that the more stable and lucrative specialty egg business is the correct strategy going forward for the company. In addition, with cost-cutting initiatives in place, Cal-Maine hopes that it can survive the cyclical downturn, and keep producing good results for long-term investors.