Shares of St. Jude Medical closed 0.2 percent higher, recovering earlier losses, after a temporary trading halt on Friday afternoon.
The stock fell 2.5 percent in intraday trade before the halt.
On Thursday, Muddy Waters Capital published a report announcing its short position in St. Jude. The firm alleged that the company's cardiac devices are vulnerable to cyber attacks, citing a study conducted by cybersecurity research firm MedSec.
These alleged security issues mean that "St. Jude's business faces some significant risk of recall for an extended period of time," Carson Block, founder of Muddy Waters, said in an interview on CNBC's "Closing Bell."
MedSec was unable to find encryption or authentication built into the protocol of St. Jude's devices, CEO Justine Bone said on "Closing Bell." She said that while her firm was able to find a few vulnerabilities in all the leading manufacturers of cardiac devices, the issues with St. Jude's devices were exceptional.
"St. Jude Medical really stood out as exceptionally falling far behind when it comes to their attention to the integrity and security of their product range, which is why we felt that we had to take the drastic action that we did," Bone said.
On Friday, St. Jude refuted Muddy Water and MedSec's claims, saying that while the company "would have preferred the opportunity to review a detailed account of the information, based on available information, we conclude that the report is false and misleading."
St. Jude said it is standing "behind the security and safety of our devices as confirmed by independent third parties and supported through our regulatory submissions." In particular, the company took issue with the testing methodology, saying that the report lacks detail and "includes many inconsistencies."