Bio-Rad’s stock leads the S&P 500 decliners, as they suffer the biggest selloff in 36 years after disappointing results.

Shares of Bio-Rad Laboratories Inc. BIO tumbled 17.5% toward their worst day in 36 years, after the maker of products for the life science research and clinical diagnostics markets reported first-quarter results that missed expectations, amid a drop in COVID-related sales, and cut its full-year outlook. The stock, which paced the S&P 500’s SPX decliners, was headed for the biggest one-day decline since it plunged 23.5% on Oct. 20, 1987. The company reported late-Thursday first-quarter sales that fell 3.3% from a year ago to $676.8 million, below the FactSet consensus of $690.0 million, as COVID-related sales dropped to…