The investment bank cut its price target on Quest's shares and noted recently passed legislation that it believes will put pricing pressure on the company.
The investment bank gave PerkinElmer an Outperform rating with a $114 stock price target and Hologic an In Line rating with a $55 stock price target.
Pressure associated with competition and reimbursement may erode GenMark's market share and product pricing, JP Morgan said.
The investment bank adjusted its December 2020 price target for Luminex's stock to $21 and for Accelerate Diagnostics' stock to $16.
Evercore noted that while Qiagen is on target to hit previously issued 2020 financial targets, its recently issued long-term guidance for 2023 is less of a sure thing.
The investment firm also reduced its price target to $30 per share from $37 citing "lower overall conviction" that Myriad would meet its revenue projections.
The investment bank downgraded LabCorp's shares to a Hold rating from Buy and lowered the target price on the stock to $162 from $195.
The investment bank cited disappointing first quarter financial results, a slow uptake to the business, and competitive pressures for the downgrade.
Despite the downgrade, the investment bank described NeoGenomics as "well-positioned" to grow its customer base in multiple customer segments.
The 360Dx Index was down 3 percent in February, reflecting similar losses in the broader markets. GenMark Diagnostics and Opko Health were the biggest decliners.