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What: Myriad Genetics (MYGN 0.16%) is down 33% at 12:35 p.m. EDT after releasing disappointing fiscal fourth quarter earnings and guidance for fiscal year 2017 after the bell Tuesday.

So what: Revenue was down just 3% in Myriad Genetics' fourth fiscal quarter, but the largest segment, hereditary cancer testing, fell 7% year over year as competition for its tests resulted in lower volumes and some declines in prices as the company tries to compete.

That competition is going to continue into the next fiscal year although it'll be made up for by Myriad Genetics' new tests in other areas. For next fiscal year, Myriad Genetics expects to record between $740 million and $760 million in revenue, which is basically flat compared to the $753.8 million it brought in during the recently closed fiscal quarter.

Unfortunately, the bottom line doesn't look nearly as flat year over year. Adjusted earnings per share for the upcoming fiscal year are expected to be in the $1.00 to $1.10 per share range, down sharply from the $1.63 per share Myriad earned in fiscal 2016.

Some of the decline comes from increased research and development expenses, which is a reasonable investment if it pays off. The acquisition of Assurex, which is scheduled to close around Oct. 1, accounts for $0.20 per share of the decline as many of the tests aren't covered by insurers yet and the interest Myriad is paying on debt to make the acquisition. Again, that's an investment in the future, but it's hurting the fiscal year 2017 expectations.

Now what: Myriad Genetics has moved to diversify away from its hereditary caner tests, but that's going to take time. The Assurex acquisition, for example, won't be accretive to earnings until the first half of fiscal year 2018. Investors willing to wait could have a nice payoff from here, but they risk the possibility that the hereditary cancer testing business declines faster than the new products can come online.