PRA Health Sciences Inc. has authorized a $500 million share repurchase program, the company announced Tuesday.

Effective immediately, the repurchase program means that the company can buy shares of its common stock including open market purchases, privately-negotiated transactions, secondary offerings and block trades.

The company is not obligated to buy any amount of its common stock under the repurchase program, which will expire at the end of 2021.

PRA Health Sciences is a contract research organization based in Raleigh. The company’s shares were trading at $98.80 Wednesday, up $1.21.