Check out which companies are making headlines after the bell:
Shares of Healthcare Services Group rose more than 4 percent in extended trading after beating per-share estimates from Thomson Reuters on its second-quarter earnings report. The company said its quarterly revenue rose nearly 22 percent from the year before to $470.88 million.
Paccar shares tumbled more than 2 percent in extended trading. S&P said Tuesday afternoon that it had assigned a stable rating to its financing subsidiary.
Shares of Humana fell nearly 3 percent in after-hours trading after Central Bank & Trust cut its stake in the health care provider by 5.6 percent, according to a recent filing with the Securities and Exchange Commission.
Shares of NRG Energy jumped more than 3 percent in extended trading after the company announced that it would release the results of its business review to transform the company in a conference call Wednesday.