Shares of Cardinal Health Inc. (CAH) plunged by 21% to $50.80 on Thursday after the company announced that its earnings for the remainder of the year will be worse than expected. 

The company said that a tax rate of 37.5% in its most recent quarter hurt its bottom line at a time when most companies are benefitting from the corporate tax cut signed by the Trump administration last year. 

The integrated healthcare services company cut its full-year earnings guidance to between $4.85 and $4.95 per share from its previous view between $5.25 and $5.50 per share. In addition to the tax issue, the company's loss of a contract with PharMerica and lower drug prices are responsible for the bearish outlook. 

The company reported revenue of $33.6 billion in the third quarter, in line with analysts' expectations while earnings of $1.39 per share fell short of expectations.

"We recognize that today's results did not meet your expectations or ours. [Next year} will be more challenging than previously expected," CEO Mike Kaufman said. 

The fallout was felt by much of the industry, with competitors McKesson Corp. (MCK) and AmerisourceBergen Corp. (ABC) declining in sympathy with the company. 

McKesson shares closed down 5.2% while AmerisourceBergen fell 7.4% on the day.