Friday saw the return of volatility to the stock market, although major benchmarks recovered substantially from their worst levels of the day. At one point, the Dow Jones Industrials were down more than 350 points following news that former Trump administration National Security Advisor Gen. Michael Flynn had pleaded guilty to a charge of lying to the FBI. Flynn's cooperation with the special counsel examining the role that Russia allegedly played in the 2016 presidential election raised fears of what further investigation might expose. Yet throughout the rest of the day, stocks regained lost ground, leading to only modest declines by the close. Moreover, some did quite well, and Ambarella (AMBA 0.58%), Foundation Medicine (FMI), and Mylan (MYL) were among the best performers on the day. Below, we'll look more closely at these stocks to tell you why they did so well.

Ambarella takes a pretty picture

Shares of Ambarella finished higher by 14% after the camera technology specialist reported its third-quarter financial results. At first glance, the company's numbers didn't look all that strong, with revenue sinking more than 11% and adjusted net income dropping by more than a third from the previous year's quarter. Yet Ambarella's performance was still better than many investors had expected, and positive comments from executives about the prospects for its newest product line led shareholders to conclude that the camera-tech company is in good position to take advantage of demand from areas like automotive, security, and other computer vision applications. Despite continued pressure on the top line, Ambarella is hopeful that it's getting itself turned around.

Camera mounted on circuit board.

Image source: Ambarella.

Foundation Medicine gets a key approval

Foundation Medicine stock soared 18% in the wake of the company receiving positive news from the U.S. Food and Drug Administration. The FDA approved the FoundationOne CDx comprehensive genomic profiling test, which Foundation Medicine created in order to help healthcare professionals diagnose and treat solid tumors in cancer patients. The test will not only help doctors figure out which patients might benefit from certain treatments, but also could help direct future research toward avenues that are mostly likely to be effective. With the trend toward personalized medicine gaining momentum, the FDA's decision could prove to be a milestone not only for Foundation Medicine but for the entire industry.

Mylan gains on Amazon speculation

Finally, shares of Mylan gained 4%. The pharmaceutical company received FDA approvals for a couple of its treatments, including one to treat breast and stomach cancer and another that acts as a blood-thinning medication. However, one report said that Mylan was among the companies that (AMZN 0.23%) might have talked with about the idea of the e-commerce giant looking at beginning pharmacy operations. With Mylan having struggled due to falling sales, some investors hope that a collaboration with Amazon could prove to be an important catalyst for the drugmaker's turnaround efforts. It would nevertheless likely take more than just a minor partnership to make a meaningful difference to Mylan's performance going forward.