Volatility remained in full force on Wall Street on Friday, and major benchmarks finished in the red to end a painful week for investors. Disappointing financial results from two of the biggest technology companies in the market set the tone for substantial declines, with the Nasdaq Composite once again leading other indexes downward. Yet even amid deepening concerns about the market's future, some stocks managed to buck the trend and produce impressive gains. WisdomTree Investments (NASDAQ:WETF), National Instruments (NASDAQ:NATI), and eHealth (NASDAQ:EHTH) were among the best performers on the day. Here's why they did so well.

WisdomTree grows assets under management

Shares of WisdomTree Investments finished higher by 9% after the company reported its third-quarter financial results. The exchange-traded fund provider said that adjusted net income jumped by more than 80% from year-earlier levels, with a 26% gain in operating revenue. WisdomTree built up its base of assets under management by $12.7 billion compared to the third quarter of 2017, with key acquisitions helping to offset some modest outflows. CEO Jonathan Steinberg noted that "with increasing pressure being exerted on legacy product structures and business models, WisdomTree has always operated with an eye toward the future and is well-positioned to navigate this environment." Even with today's gains, though, the stock is down sharply over the past year, and so it'll be important for WisdomTree to survive and thrive in a more volatile environment.

Logo showing a tree and the WisdomTree trademark.

Image source: WisdomTree.

National Instruments perks up

National Instruments stock jumped 17% in the wake of the company's third-quarter financial report. The maker of tools and systems for scientists and engineers said that revenue rose 8% on a 13% rise in total orders received. Bigger customers were an even greater driver of performance for NI, as large orders of more than $20,000 soared by 21% from year-earlier levels. NI's narrowing of its focus to its highest-potential products has worked out well, and the company sees even better times ahead. That's good news for a player in an industry that's starting to see some concerns about a possible cyclical downturn at some point in the future.

eHealth looks strong

Finally, shares of eHealth picked up 14%. The online health insurance exchange provider enjoyed a 30% rise in revenue during the third quarter of 2018 compared to the previous year's period, and eHealth cut its adjusted pre-tax operating losses nearly in half year over year. The fourth quarter is a key time for eHealth because it's when most people are looking at healthcare options, and CEO Scott Flanders said that "we are confident in our operational readiness for this selling season, our ability to generate strong Medicare enrollment growth, and our ability to deliver on our full year financial guidance." With today's move, eHealth stock is up 85% so far this year, and investors hope that business success could bring even more share-price gains.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool recommends National Instruments and WisdomTree Investments. The Motley Fool has a disclosure policy.