J.P. Morgan slashed its price target to $6 a share from $10 while reducing its rating to underweight from neutral.
And William Blair analyst John Kreger cut his recommendation on the company to market perform from outperform.
SmileDirectClub shares at last check were down 17% to $5.56.
The Nashville company reported a second-quarter net loss of 14 cents a share on revenue of $174.2 million.
Analysts surveyed by FactSet were expecting the company to report a net loss of 12 cents a share on revenue of $198.5 million.
For the year, the company expects revenue of $750 million to $800 million. FactSet's call for the year: $783.4 million.
The company said the April cyberattack and the "lasting economic effects from COVID on our target demographic" played a role in the company's quarterly results.
But the company's CEO is optimistic about SmileDirectClub's prospects.
The company aims to extend its telehealth platform for orthodontia by emphasizing customer experience, improving consumer perception around credibility and driving positive sentiment with its Challenger campaign, Chief Executive David Katzman said in a statement.
Sales and marketing as a percentage of total revenue is expected to be in the 50% to 55% range through the second half, SmileDirectClub said.