The stock market finished strong on Friday, celebrating the good news on the macroeconomic front that came in this morning's U.S. employment report. Unemployment dropped to its lowest level in years, with a greater number of new jobs created than those watching the market had expected. Overall, investors seem ready to buy at the first sign of good news, and that helped power major benchmarks to gains of roughly 1%. Some stocks did even better. Nektar Therapeutics (NASDAQ:NKTR), Ambac Financial Group (NASDAQ:AMBC), and Zuora (NYSE:ZUO) were among the best performers on the day. Here's why they did so well.

Nektar looks for approval

Shares of Nektar Therapeutics rose 12.5% after the biotech company announced its submission of a New Drug Application for a new candidate treatment. Nektar's NKTR-181 is intended to treat patients suffering from chronic lower back pain. The drug is an opioid, but as Chief Development Officer Dr. Steve Doberstein observed, "This innovative investigation medicine separates analgesic efficacy from the high levels of euphoria that too often lead to the abuse and addiction of traditional opioids." After promising phase 3 clinical trials for NKTR-181, investors are hopeful that the U.S. Food and Drug Administration will approve Nektar's submission in due course.

Two-story glass office building, parking lot, and one-story entry building with Nektar logo on it.

Image source: Nektar Therapeutics.

Ambac gets an invitation it can't refuse

Ambac Financial Group stock gained 9% in the wake of the financial insurance specialist's shares getting invited into the S&P SmallCap 600 index. In a complicated series of domino effects, a merger of two utility giants will create an opening in the S&P Midcap 400 index, which S&P Dow Jones Indices will replace with a life-sciences company that's currently in the S&P SmallCap 600. That in turn will create the vacancy that Ambac will fill. The company has seen plenty of volatility related to various exposures it has, but its efforts to manage its risk have thus far been fairly successful.

Zuora makes a good first impression

Finally, shares of Zuora soared 19%. The newly public cloud computing specialist announced strong fiscal first-quarter financial results in its first report since its IPO, including total revenue gains of 60% on a 39% jump in subscription-based revenue. CEO Tien Tzuo made positive comments about Zuora, noting that as the "only public company 100% focused on the expanding subscription economy," Zuora's results "reflect the continuing adoption of the subscription business model by companies across all industries around the world." With such a huge addressable market, it's no surprise that Zuora's joining a host of promising cloud tech companies in the space.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.