Reddit Set to Join S&P 500 and Sun Communities to Join S&P MidCap 400

Rhea-AI Summary

S&P Dow Jones Indices announced upcoming changes to the S&P 500 and S&P MidCap 400. Effective prior to trading on August 18, 2026, Reddit (NYSE: RDDT) will be added to the S&P 500, replacing AvalonBay Communities (NYSE: AVB), which is being acquired by S&P 500 constituent Equity Residential (NYSE: EQR).

After that merger closes, the combined company will be renamed Vivmark Residential (NYSE: VMRK) and will remain in the S&P 500. Effective prior to trading on August 20, 2026, Sun Communities (NYSE: SUI) will join the S&P MidCap 400, replacing Webster Financial (NYSE: WBS), which is being acquired by Banco Santander (NYSE: SAN). The table specifies each change’s index, ticker and GICS sector.

Positive

• Reddit added to S&P 500 effective August 18, 2026
• Sun Communities added to S&P MidCap 400 effective August 20, 2026
• Equity Residential–AvalonBay merger will create Vivmark Residential, remaining in S&P 500
• Index membership for Vivmark Residential confirmed in S&P 500 post-merger

Negative

• AvalonBay Communities removed from S&P 500 on August 18, 2026
• Webster Financial removed from S&P MidCap 400 on August 20, 2026

AI-generated analysis. How Rhea-AI works. Not financial advice.

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NEW YORK, Aug. 13, 2026 /PRNewswire/ -- S&P Dow Jones Indices will make the following changes to the S&P 500 and S&P MidCap 400: 

• Reddit Inc. (NYSE: RDDT) will replace AvalonBay Communities Inc. (NYSE: AVB) in the S&P 500 effective prior to the opening of trading on Tuesday, August 18. S&P 500 constituent Equity Residential (NYSE: EQR) is acquiring AvalonBay Communities in a deal expected to be completed soon, pending final conditions. Post merger, the combined company will be renamed Vivmark Residential (NYSE: VMRK) and will remain in the S&P 500.
• Sun Communities Inc. (NYSE: SUI) will replace Webster Financial Corp. (NYSE: WBS) in the S&P MidCap 400 effective prior to the opening of trading on Thursday, August 20. Banco Santander S.A. (BMEX / NYSE: SAN) is acquiring Webster Financial in a deal expected to be completed soon pending final 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
August 18, 2026	S&P 500	Addition		Reddit	RDDT	Communication Services
August 18, 2026	S&P 500	Deletion		AvalonBay Communities	AVB	Financials
August 20, 2026	S&P MidCap 400	Addition		Sun Communities	SUI	Real Estate
August 20, 2026	S&P MidCap 400	Deletion		Webster Financial	WBS	Financials

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.

S&P Dow Jones Indices is a division of S&P Global (NYSE: SPGI), which provides essential intelligence for individuals, companies, and governments to make decisions with confidence. For more information, visit www.spglobal.com/spdji/en/.

FOR MORE INFORMATION:

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View original content:https://www.prnewswire.com/news-releases/reddit-set-to-join-sp-500-and-sun-communities-to-join-sp-midcap-400-302851432.html

SOURCE S&P Dow Jones Indices

FAQ

What S&P 500 change is Reddit (NYSE: RDDT) involved in on August 18, 2026?

Reddit will be added to the S&P 500 effective before trading on August 18, 2026, replacing AvalonBay Communities. According to S&P Dow Jones Indices, Reddit will be included in the Communication Services sector within the index.

Why is AvalonBay Communities (NYSE: AVB) being removed from the S&P 500?

AvalonBay Communities will be deleted from the S&P 500 as Reddit is added. According to S&P Dow Jones Indices, AvalonBay is being acquired by Equity Residential, and the combined company will be renamed Vivmark Residential and remain in the S&P 500.

What happens to Equity Residential (NYSE: EQR) after acquiring AvalonBay Communities?

Following completion of the acquisition, Equity Residential and AvalonBay will form Vivmark Residential (NYSE: VMRK), which will remain in the S&P 500. According to S&P Dow Jones Indices, this change occurs after the merger closes, with index continuity preserved.

When will Sun Communities (NYSE: SUI) join the S&P MidCap 400 index?

Sun Communities will be added to the S&P MidCap 400 effective before the market opens on August 20, 2026. According to S&P Dow Jones Indices, it will replace Webster Financial in the Real Estate sector classification.

Why is Webster Financial (NYSE: WBS) being removed from the S&P MidCap 400?

Webster Financial will be deleted from the S&P MidCap 400 on August 20, 2026. According to S&P Dow Jones Indices, Banco Santander is acquiring Webster Financial, prompting its removal from the index once Sun Communities is added.

What new ticker and name will the combined Equity Residential and AvalonBay company use in the S&P 500?

The combined company will be named Vivmark Residential with ticker VMRK and remain in the S&P 500. According to S&P Dow Jones Indices, this follows completion of Equity Residential’s acquisition of AvalonBay Communities.