DocuSign Inc. ( NASD:DOCU ) will replace MDU Resources Group Inc. ( NYSE:MDU ) in the S&P MidCap 400, and MDU Resources Group will replace Chuy's Holdings Inc. ( NASD:CHUY ) in the S&P SmallCap 600 effective prior to the opening of trading on Friday, October 11. S&P 500 constituent Darden Restaurants Inc. ( NYSE: DRI ) is acquiring Chuy's Holdings in a deal expected to be completed soon, pending final closing conditions. MDU Resources announced its intention to spin-off a company later this month.

Following is a summary of the changes that will take place prior to the open of trading on the effective date:

DocuSign shares jumped 5.6% in extended trading.