The study said that Cologuard was an "inefficient screening option" for colorectal cancer given its cost as compared to other CRC screening methods.
Of the 27 companies in the index, 14 firms' stocks were down, while 13 companies' share prices increased.
Of the 27 companies in the index, 12 firms' share prices retreated last month, 14 companies' stocks increased, and one firm's share value was flat.
Nasdaq told the company that its shares have failed to meet a minimum $1 per share closing price for 30 consecutive days and may face delisting action.
Other big gainers last month included Accelerate Diagnostics and Natera, and share prices of 23 of the 27 companies in the index increased month over month.
The firm said it needs more time to ensure that the DetermaVu assay is providing the most consistent and sensitive results for patients.
The investment bank gave Danaher a Neutral rating and a $148 price target on the firm's shares, while it gave Agilent an Overweight rating with an $83 price target.
The broader market drove down the stock prices of many diagnostics companies. Natera, Guardant Health, and CareDx paced the gainers.
The number of gainers outpaced decliners 21 to six, and the index outpaced the Dow Jones Industrial Average, the Nasdaq Composite, and the Nasdaq Biotech.
Many diagnostic firms saw gains in their stock prices last month as Invitae and NantHealth also saw healthy increases.