Shares of Illumina Inc. plummeted 16% in active morning trading Friday, after Bank of America Merrill Lynch swung to being bearish from bullish in the wake of the genetics company's revenue warning. Analyst Derik de Bruin cut his rating two notches to underperform from buy, and slashed his price target to $290 from $355. That downgrade follows the company's disclosing late Thursday that it now expects second-quarter revenue of $835 million, below the FactSet consensus of $888.3 million. "The miss was particularly surprising to us given positive commentary from management in recent months, and the number of issues that cropped up in the quarter," de Bruin wrote in a note to clients. While he's still upbeat on Illumina's positioning in the DNA sequencing/genomics market, he now sees "few near-term catalysts." The stock, on track to suffer the biggest one-day drop since October 2016, was still up 1.8% year to date, while the Dow Jones Industrial Average has gained 17%.