Corebridge Financial Set to Join S&P MidCap 400

Rhea-AI Summary

Corebridge Financial (NYSE:CRBG) will be added to the S&P MidCap 400 prior to the open on Dec 17, 2025, replacing Allete (NYSE:ALE), which will be deleted on the same date.

The change follows an announced acquisition of Allete by Canada Pension Plan Investment Board and Global Infrastructure Partners, which is expected to close soon pending final conditions.

Positive

• Corebridge (CRBG) added to S&P MidCap 400 effective Dec 17, 2025
• Index inclusion may increase passive demand for CRBG shares

Negative

• Allete (ALE) removed from S&P MidCap 400 effective Dec 17, 2025
• Allete pending acquisition—transaction completion conditional on closing conditions

Market Context

This announcement confirms that ALLETE will be deleted from the S&P MidCap 400 on Dec 17, 2025, foll...

Analysis

This announcement confirms that ALLETE will be deleted from the S&P MidCap 400 on Dec 17, 2025, following its acquisition and planned delisting from the NYSE. It continues a sequence of regulatory approvals and merger milestones over 2025. With the stock trading close to its 52-week high and recent volume elevated, the key considerations are timing of closing, final index-related flows, and how quickly trading in ALE common shares is wound down.

Key Figures

Index change date: Dec 17, 2025 Index action: Deletion from S&P MidCap 400

2 metrics

Index change date Dec 17, 2025 Effective date for ALE deletion from S&P MidCap 400

Index action Deletion from S&P MidCap 400 Replaced by Corebridge Financial due to acquisition of ALLETE

Historical Context

5 past events · Latest: Dec 11 (Positive)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Dec 11	Merger approval order	Positive	+0.3%	Final MPUC written order approving acquisition and confirming closing timeline.
Oct 31	Earnings and sale	Negative	-0.1%	Softer Q3 2025 EPS and revenue while awaiting MPUC written merger order.
Oct 28	Earnings preview	Neutral	+0.1%	Scheduling announcement for Q3 2025 financial results release date.
Oct 03	Regulatory approval	Positive	+0.7%	Unanimous MPUC approval of acquisition and customer benefit commitments.
Aug 07	Quarterly earnings	Negative	-0.4%	Q2 2025 EPS and segment net income declining versus prior year, plus transaction costs.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Across recent merger and earnings updates, ALE’s share price has consistently moved in the same direction as the apparent sentiment of each announcement, with no clear instances of divergence.

Recent Company History

Over the last six months, ALE’s news flow has been dominated by its pending acquisition by CPP Investments and Global Infrastructure Partners, alongside softer earnings. Regulatory milestones from the Minnesota Public Utilities Commission on October 3, 2025 and the written order on December 11, 2025 advanced the deal toward closing and NYSE delisting. Quarterly results on August 7 and October 31, 2025 highlighted lower EPS and transaction expenses. The current index-related announcement follows this sequence of merger-closure steps and market adjustments.

Key Terms

s&p midcap 400, gics sector, s&p 500, dow jones industrial average

4 terms

s&p midcap 400 financial

"Dec 17, 2025 | S&P MidCap 400 | Addition | Corebridge Financial"

The S&P MidCap 400 is a group of 400 companies that are smaller than the big, well-known corporations but larger than tiny startups. It helps investors see how medium-sized companies are performing in the stock market, acting like a barometer for this middle-sized group of businesses.

gics sector financial

"Ticker | GICS Sector Dec 17, 2025 | S&P MidCap 400 |"

GICS sector is one of the major industry groupings from the Global Industry Classification Standard, a system that sorts companies into consistent categories (like Technology or Health Care) based on the primary business they do. Investors use these sectors like folders in a filing cabinet to compare companies, build diversified portfolios, and track how whole parts of the market are performing rather than focusing on single stocks.

s&p 500 financial

"home to iconic financial market indicators, such as the S&P 500® and the Dow"

The S&P 500 is a broad stock market index that tracks the performance of 500 large U.S. companies, weighted so bigger firms have a larger impact. Investors use it like a thermometer or benchmark to judge how the overall U.S. stock market or a portfolio is doing; movements in the index influence investor sentiment, fund performance, and many passive investment products that aim to match its returns.

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dow jones industrial average financial

"such as the S&P 500® and the Dow Jones Industrial Average®."

A stock market index that tracks the share prices of a small group of large, well-known companies to give a quick snapshot of how the broader market is doing. Think of it like a thermometer for the stock market: it uses a handful of heavyweight firms as representative samples to show whether investor sentiment is rising or falling, which helps investors gauge market trends and compare performance over time.

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

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NEW YORK, Dec. 12, 2025 /PRNewswire/ -- Corebridge Financial Inc. (NYSE: CRBG) will replace Allete Inc. (NYSE: ALE) in the S&P MidCap 400 effective prior to the open of trading on Wednesday, December 17. Canada Pension Plan Investment Board and Global Infrastructure Partners are acquiring Allete in a deal expected to close soon, pending final closing conditions.

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

Effective Date	Index Name	Action	Company Name	Ticker	GICS Sector
Dec 17, 2025	S&P MidCap 400	Addition	Corebridge Financial	CRBG	Financials
Dec 17, 2025	S&P MidCap 400	Deletion	Allete	ALE	Utilities

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View original content:https://www.prnewswire.com/news-releases/corebridge-financial-set-to-join-sp-midcap-400-302640515.html

SOURCE S&P Dow Jones Indices

FAQ

When will Corebridge (CRBG) join the S&P MidCap 400?

Corebridge will be added to the S&P MidCap 400 prior to the open on Dec 17, 2025.

Why is Allete (ALE) being removed from the S&P MidCap 400 on Dec 17, 2025?

Allete is being deleted from the index because it is the target of a pending acquisition by Canada Pension Plan Investment Board and Global Infrastructure Partners.

What does the Dec 17, 2025 index change mean for CRBG shareholders?

Index addition typically increases passive fund demand for CRBG shares around the effective date.

Is the Allete acquisition final and how does it affect ALE shares?

The acquisition is expected to close soon but remains subject to final closing conditions.

Which tickers and sectors are affected by the Dec 17, 2025 change?

CRBG (Financials) will be added and ALE (Utilities) will be deleted from the S&P MidCap 400 on Dec 17, 2025.