Willis Group, Adeptus Health Moving After Stocks Join S&P 500 And S&P SmallCap 600 Respectively

Shares of Willis Group Holdings Limited WSH traded up more than 2 percent during the after-hours session Monday -- and are up more than 4 percent on Tuesday -- following news out of S&P Dow Jones Indices the company's stock will be added to the illustrious S&P 500 index.

The change will take place after the close of trading on Monday, January 4.

Willis Group will be replacing Fossil Group Inc FOSL, which will be bumped down to the S&P MidCap 400. Fossil, in turn, will be replacing Towers Watson, which is being merged with none other than Willis Group.

The S&P release mentioned the combined Willis Group plus Towers Watson entity will trade under company name Willis Towers Watson plc and ticker symbol "WLTW."

Also in the release, S&P announced Adeptus Health Inc ADPT will be replacing Ferroglobe plc GSM in the S&P SmallCap 600 index.

Adeptus Health is up nearly 7 percent on Tuesday morning.