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S&P Global Inc, Arrowhead Pharmaceuticals Inc, ADT Inc, Ciena Corp

Ciena Set to Join S&P 500; Arrowhead Pharmaceuticals to Join S&P MidCap 400; ADT and OneSpaWorld Holdings to Join S&P SmallCap 600

NEW YORK , Feb. 4, 2026 /PRNewswire/ -- S&P Dow Jones Indices will make the following changes to the S&P 500, S&P MidCap 400, S&P SmallCap 600: 

  • S&P MidCap 400 constituent Ciena Corp. (NYSE: CIEN) will replace Dayforce Inc. (NYSE: DAY) in the S&P 500, S&P SmallCap 600 constituent Arrowhead Pharmaceuticals Inc. (NASD: ARWR) will replace Ciena in the S&P MidCap 400, and ADT Inc. (NYSE: ADT) will replace Arrowhead Pharmaceuticals in the S&P SmallCap 600 effective prior to the opening of trading on Monday, February 9. Thoma Bravo L.P. acquired Dayforce in a deal that closed today.
  • OneSpaWorld Holdings Ltd. (NASD: OSW) will replace Dynavax Technologies Corp. (NASD: DVAX) in the S&P SmallCap 600 effective prior to the opening of trading on Tuesday, February 10. Sanofi is acquiring Dynavax Technologies in a deal expected to be completed soon pending final closing conditions.

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

Effective Date

Index Name

Action

Company Name

Ticker

GICS Sector

Feb 9, 2026

S&P 500

Addition

Ciena

CIEN

Information Technology

Feb 9, 2026

S&P 500

Deletion

Dayforce

DAY

Industrials

Feb 9, 2026

S&P MidCap 400

Addition

Arrowhead Pharmaceuticals

ARWR

Health Care

Feb 9, 2026

S&P MidCap 400

Deletion

Ciena

CIEN

Information Technology

Feb 9, 2026

S&P SmallCap 600

Addition

ADT

ADT

Consumer Discretionary

Feb 9, 2026

S&P SmallCap 600

Deletion

Arrowhead Pharmaceuticals

ARWR

Health Care

Feb 10, 2026

S&P SmallCap 600

Addition

OneSpaWorld Holdings

OSW

Consumer Discretionary

Feb 10, 2026

S&P SmallCap 600

Deletion

Dynavax Technologies

DVAX

Health Care

ABOUT S&P DOW JONES INDICES

S&P Dow Jones Indices is the largest global resource for essential index-based concepts, data and research, and home to iconic financial market indicators, such as the S&P 500® and the Dow Jones Industrial Average®. More assets are invested in products based on our indices than products based on indices from any other provider in the world. Since Charles Dow invented the first index in 1884, S&P DJI has been innovating and developing indices across the spectrum of asset classes helping to define the way investors measure and trade the markets.

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Cision View original content:https://www.prnewswire.com/news-releases/ciena-set-to-join-sp-500-arrowhead-pharmaceuticals-to-join-sp-midcap-400-adt-and-onespaworld-holdings-to-join-sp-smallcap-600-302679569.html

SOURCE S&P Dow Jones Indices