On Wednesday, the stock fell to $33.53 at the close, with volume of just under 1.4 million shares.
Jolie explained her decision in an op-ed piece in the New York Times.
"The cost of testing for BRCA1 and BRCA2, at more than $3,000 in the United States, remains an obstacle for many women," Jolie wrote, referring to the genes. A mutation of the genes can indicate a greater chance of cancer.
Myriad spokesman Ron Rogers said Wednesday that while the company wished Jolie well and was pleased that she encouraged other women with a family history of breast and ovarian cancer to get tested, the company disagreed with her on the cost being an obstacle. Rogers said insurance covers 95 percent of patients with a co-pay of about $100. For those without insurance, the company offers discounts, and provided 5,000 free tests in the last three years. The Affordable Care Act will require insurers to cover such tests.
"Everyone who is at risk should absolutely go get the BRCA test," Julie Kessel, Cigna's senior medical director overseeing the coverage policy unit, was quoted as saying in a story on Marketwatch.com.
Women who could not afford the test in previous years, including one from Williamsport, Pa., were among the original plaintiffs in a lawsuit that is pending before the U.S. Supreme Court. The basic issue is whether Myriad - or any company or person - should be allowed to patent on a human gene. The court heard oral arguments April 15 and is likely to issue a decision before the end of the current term in June.
Myriad's stock price had already risen in the last week, bolstered by its quarterly earnings report. The company is heavily dependent on the revenue from testing for these genes.
"Revenue from the BRACAnalysis test, which represented 74 percent of total revenue in the third quarter, was $115.4 million, a 9 percent increase over the same period of the prior year," Myriad said in a news release that accompanied its report.
Monday's Supreme Court decision on seed patents in favor of Monsanto in Bowman v. Monsanto et al. might have also been a factor. Marketwatch.com reported that William Blair analyst Amanda Murphy said in an e-mail that she believed the Monsanto decision was a bigger factor in Tuesday's stock movement than Jolie's announcement.
Murphy said the court recognized the investment that companies like Monsanto have to make in research and development, and that issue was also discussed during oral arguments in the Myriad case.
Contact David Sell at 215-854-4506, firstname.lastname@example.org, or follow on Twitter @phillypharma. Read his blog at www.philly.com/phillypharma.