Friday gave the stock market a solid start to the new quarter, and investors generally reacted favorably to economic data suggesting the continued strength of the U.S. labor market. Nonfarm payrolls rose by a greater-than-expected 215,000 jobs in March, but the arguably better news came from the unemployment rate.

Even though the measure climbed a tenth of a percentage point, to 5%, the labor participation rate rose by the same amount, to 63%, and that was primarily responsible for the rise in the unemployment rate. Major stock-market benchmarks rose about two-thirds of a percent, but many stocks rose more sharply. Among them were Regeneron Pharmaceuticals (NASDAQ:REGN), Tronox (NYSE:TROX), and Office Depot (NASDAQ:ODP).

Regeneron Pharmaceuticals finished up 12% after the company reported that its proposed dermatitis treatment dupilumab had produced encouraging data in two phase 3 studies. Regeneron said that using the drug helped improve measures of disease severity, as well as skin clearing, itching, quality of life, and mental health. As Regeneron Chief Scientific Officer George Yancopoulos commented, "These data provide strong evidence that the IL-4 and IL-13 signaling pathway is a fundamental driver of inflammation in atopic dermatitis."

He went on to note that "dupilumab blocked the aberrant activation of this pathway, resulting in significant efficacy without evidence of immune-suppressing side effects." With Regeneron and partner Sanofi expecting to file for approval later this year, investors hope that the breakthrough therapy will gain quick approval, and produce solid sales in the near future.

Tronox gained 7% in the wake of new price increases taking effect for sales of titanium dioxide. Late Thursday, the chemical and mineral specialist said that it would boost prices by $175 per metric ton in the U.S., and by 175 euro per metric ton in European markets for all of its titanium dioxide grades.

The pigment is used in everything from paint to food coloring and sunscreen, and price increases throughout the industry have appeared recently in order to offset multiyear weakness in the industry. Even though the move is the second price increase by Tronox so far in 2016, industry analysts are unclear whether raising prices will be able to offset fully the pressures that the titanium dioxide industry has seen.

Finally, Office Depot climbed 6%. A trial over the office-supply store chain's proposed merger with Staples has been going on for a couple of weeks now, and the judge in the case said that he wouldn't allow testimony by the Federal Trade Commission that could potentially have blocked the deal on anti-competitive grounds. The primary question in the FTC case is whether e-commerce poses a creditable competitive obstacle to an alleged Office Depot-Staples monopoly in the corporate office-supply market. The exclusion of expert testimony will make it more difficult for the FTC to make that case, and investors therefore believe that the merger is more likely to go through as planned.