Centene Corp. (CNC) and Laboratory Corp. of America Holdings (LH) were among the healthcare stocks in the green on Tuesday, Feb. 6, amid a volatile trading day in the stock market. The Dow Jones industrial average ended the trading session up 567 points, or 2.3%, after a day of wild swings. The S&P 500 index finished with a gain of 46.2 points, or 1.7%.

Shares of Centene closed up 4.3% at $103.67, and LabCorp finished at $168.67, up 2.5%.

St. Louis-based Centene on Tuesday reported fourth-quarter adjusted diluted earnings per share of 97 cents on revenue of $12.81 billion. Analysts had projected, on average, adjusted EPS of 93 cents on revenue of $12.25 billion, according to Bloomberg. Centene also raised its 2018 guidance.

LabCorp, based in Burlington, N.C., reported adjusted EPS of $2.45 on net revenue of $2.8 billion for the fourth quarter. Analysts expected adjusted EPS of $2.38 on revenue of $2.7 billion.

Among the other gainers was Gilead Sciences Inc. (GILD) , which closed at $80.38, up 2.6%.

After the market close on Tuesday, the Foster City, Calif., company reported fourth-quarter non-GAAP net income per share of $1.78 on revenue of $5.9 billion. Analysts expected adjusted EPS of $1.67 on revenue of $5.71 billion.

For its part, shares of Allergan plc (AGN) finished at $168.33, up 2%. The Dublin drugmaker on Tuesday morning reported fourth-quarter non-GAAP net income per share of $4.86 on net revenue of $4.33 billion. Analysts expected, on average, adjusted EPS of $4.74 on revenue of $4.28 billion, according to FactSet Research Systems Inc.

Allergan also unveiled positive results from a clinical trial of ubrogepant for migraine treatment.

Meanwhile, shares of Merck & Co. (MRK) closed at $55.46, down 1.7%. Shares of Varian Medical Systems Inc. (VAR) ended the session down 0.9% to $118.58.

Allergan is a holding in Jim Cramer's Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer and the AAP team buy or sell AGN? Learn more now.

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