Why Illumina Stock Is Sinking Today

Shares of Illumina (ILMN -8.47%) were falling on Friday. The company's stock was down by as much as 11.4% early in the session, and was still off by 8.7% as of 2:38 p.m. ET. At that time, the S&P 500 had slid by 0.9% and the Nasdaq Composite was down 1.4%.Illumina, a biotech company that develops and manufactures genetic testing systems, reported disappointing fourth-quarter numbers after the closing bell Thursday.The numbersIllumina's revenue has stagnated or declined for several years now, and its total s ...