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 |
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SOURCE S&P Dow Jones Indices