Friday was a good day on Wall Street, as major benchmarks regained some of the ground they had lost earlier in the week. A solid employment report for September helped to allay fears that a recession might be imminent for the U.S., and investors seemed to feel more comfortable about the long-term prospects for key sectors of the market. Some individual stocks saw strong gains. SmileDirectClub (SDC -75.00%), Avaya Holdings (AVYA), and Sarepta Therapeutics (SRPT 1.88%) were among the top performers. Here's why they did so well.

SmileDirectClub puts a smile on shareholders' faces

Shares of SmileDirectClub climbed 7.5% despite getting criticism from a short-selling research company. Hindenburg Research asserted that the dental alignment specialist could see its stock fall as much as 85%, and made several inflammatory claims about SmileDirectClub's business. The tooth-aligner maker issued a statement rebutting the allegations and arguing that it's the victim of a campaign to try to prevent competition from what it terms "SmileDirectClub's disruptive business model." The stock initially fell on the report, but the company's quick and forceful response gave investors more confidence.

Person holding a clear aligner near teeth.

Image source: Getty Images.

Avaya finds a partner

Avaya Holdings saw its stock soar 31% after it announced a key partnership. The office communications company said that it would work with RingCentral to offer a new cloud-based communications platform for its clients. Under the deal, RingCentral will be Avaya's exclusive source for unified communications as a service, and RingCentral will make a $125 million preferred equity investment along with advancing $375 million more for future payments and licensing rights. For Avaya, the deal provides valuable cash to help it manage its debt and buy back stock, and investors were pleased at the long-term strategic value of the partnership as well.

Sarepta sees good results

Finally, shares of Sarepta Therapeutics finished higher by 8.5%. The gene therapy specialist said that its SRP-9003 investigational therapy showed promising results in a clinical trial of muscular dystrophy patients. The findings included improved physical function for the three participants in the survey, along with reductions in creatine kinase levels and an encouraging safety profile. The news was especially welcome after some of the challenges that Sarepta has seen with other drugs lately, but it'll still be a long time before SRP-9003 progresses enough to draw realistic conclusions about its long-term prospects.