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GenomeWeb Index Newcomers Adaptive Bio, Castle Biosciences See Steep Share Declines in September

NEW YORK – September proved a disappointing month for the GenomeWeb Index, which fell 2.6 percent after already declining 1.8 percent in August.

While the drop was in line with the Nasdaq Biotechnology Index, which lost more than 3 percent in September, the Dow Jones Industrial Average gained 2 percent and the Nasdaq gained 0.5 percent during the same period.

Adaptive Biotechnologies (-39 percent) and Castle Biosciences (-35 percent) lost more than a third of their share price in September, followed by Guardant Health (-27 percent), Exact Sciences (-24 percent), NeoGenomics Laboratories (-23 percent), and Invitae (-21 percent).

The only big gainer among GenomeWeb Index companies this month was Myriad Genetics (22 percent), with smaller increases seen by Illumina (8 percent) and Agilent Technologies (8 percent).

Adaptive Biotechnologies, a newcomer to the index that went public at the end of June, announced partnerships with Amgen and Illumina in September. Despite the positive news, it saw its stock price erode over the course of the month. Following its IPO opening price of $39.01 per share, the company's stock had risen to a height of $53.51 in early September, followed by a fairly steady decline. 

Castle Biosciences, another new company in the GenomeWeb Index, in early September reported almost tripled revenues for the second quarter but saw its stock decline gradually over the course of the month. The company's opening share price on the day of its IPO in late July was $20, and its stock climbed to $27.92 by the end of August before reversing course.

Exact Biosciences, on the other hand, saw its stock take a dive in early September after a scientific study called its Cologuard colorectal cancer screening test "an inefficient screening option." Its share price has further declined since then despite positive news from the US Food and Drug Administration, which in late September expanded the indication for Cologuard to younger people.

Guardant Health, NeoGenomics, and Invitae didn't make any announcements in September but still saw their stock go down steadily over the course of the month.

Myriad Genetics, following a big drop of its share price in August, saw its stock recover gradually in September. Mid-month, the firm announced a collaboration with researchers at the University of Leeds involving its Prolaris prostate cancer test, though the news had a small immediate effect on its share price.