Sirius XM Holdings Set to Join S&P MidCap 400

Rhea-AI Summary

Sirius XM Holdings (NASD: SIRI) will join the S&P MidCap 400, replacing Masimo (NASD: MASI), effective before the market opens on June 11, 2026. Danaher (NYSE: DHR), an S&P 500 and 100 constituent, is acquiring Masimo, with the deal expected to close after final conditions.

On June 11, 2026, Sirius XM will be added to the index as a Communication Services company, while Masimo will be removed from the index’s Health Care sector.

AI-generated analysis. Not financial advice.

Positive

• Sirius XM added to S&P MidCap 400 on June 11, 2026
• Danaher to acquire Masimo, transaction pending final conditions

Negative

• Masimo to be deleted from S&P MidCap 400 on June 11, 2026

News Market Reaction – SPGI

+1.62%

1 alert

+1.62% News Effect

On the day this news was published, SPGI gained 1.62%, reflecting a mild positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Effective date: June 11, 2026 S&P MidCap 400 size: 400 S&P 500 size: 500 +2 more

5 metrics

Effective date June 11, 2026 Index changes effective prior to market open

S&P MidCap 400 size 400 Index Sirius XM will join

S&P 500 size 500 Index including Danaher Corp.

S&P 100 size 100 Index including Danaher Corp.

First index year 1884 Year Charles Dow invented the first index

Peers on Argus

Key peers MCO, ICE, CME, MSCI and NDAQ all show negative moves today (e.g., ICE ...

Key peers MCO, ICE, CME, MSCI and NDAQ all show negative moves today (e.g., ICE -1.38%, MCO -1.63%). The momentum scanner did not flag a coordinated sector move, suggesting SPGI’s -1.73% decline reflects stock-specific or broader market factors rather than a strong, unified sector rotation.

Historical Context

5 past events · Latest: Jun 08 (Positive)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Jun 08	AI collaboration	Positive	-1.5%	Strategic collaboration with Cohere to power trusted agentic AI workflows.
Jun 05	Conference appearance	Neutral	-1.5%	Participation in Mizuho Technology Conference via investor relations fireside chat.
Jun 04	Index methodology	Neutral	+1.0%	Results of MegaCap consultation; no eligibility changes for key S&P indices.
Jun 04	AI product launch	Positive	+1.9%	Launch of agentic AI-powered Credit Memo Builder to streamline credit analysis.
Jun 02	Client ranking	Neutral	-2.6%	S&P Global Market Intelligence ranking highlighted in client’s community bank award.

Pattern Detected

Recent AI and product innovation news has produced mixed reactions: one AI launch aligned with a positive move, while another AI partnership coincided with a decline, indicating inconsistent trading responses to similar innovation headlines.

Recent Company History

Over the past week, S&P Global has issued several notable updates. Two AI-focused announcements on June 4 and June 8, 2026 highlighted new agentic AI products and a collaboration with Cohere, drawing attention to innovation in data workflows. Index-related communication on June 4 confirmed no rule changes for major S&P indices. Conference participation and third-party rankings underscored ongoing client and market engagement. Today’s index-composition news for Sirius XM again involves S&P Dow Jones Indices, extending this stream of index and data-related developments.

Regulatory & Risk Context

Short Interest: 1.54%

Short Interest

1.54% of shares outstanding

as of 2026-05-29 Days to cover: 1.95

Market Pulse Summary

This announcement highlights an index change in which Sirius XM joins the S&P MidCap 400 as Masimo e...

Analysis

This announcement highlights an index change in which Sirius XM joins the S&P MidCap 400 as Masimo exits due to an acquisition by Danaher, an S&P 500 and S&P 100 constituent. For S&P Global, it underscores the ongoing centrality of S&P Dow Jones Indices in tracking corporate actions and reshaping benchmarks. In context with recent AI initiatives and index consultations, investors may watch how index methodology, product innovation, and the Mobility spin-off collectively influence the company’s growth profile and competitive positioning.

Key Terms

s&p midcap 400, s&p 500, s&p 100, dow jones industrial average, +1 more

5 terms

s&p midcap 400 financial

"June 11, 2026 | S&P MidCap 400 | Addition | Sirius XM Holdings"

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.

s&p 500 financial

"S&P 500 & 100 constituent Danaher Corp. (NYSE: DHR)"

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.

s&p 100 financial

"S&P 500 & 100 constituent Danaher Corp. (NYSE: DHR)"

The S&P 100 is a stock market index that tracks the shares of 100 large, well‑established U.S. companies selected for size and ease of trading; think of it as a basket representing the biggest, most widely traded American firms. Investors use it as a quick read on how large‑cap, blue‑chip stocks are performing and as a benchmark for funds and derivatives; like checking the temperature of the largest businesses, movements in the index can influence portfolio choices and risk management.

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.

gics sector financial

"Ticker | GICS Sector"

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.

AI-generated analysis. Not financial advice.

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NEW YORK, June 8, 2026 /PRNewswire/ -- Sirius XM Holdings Inc. (NASD: SIRI) will replace Masimo Corp. (NASD: MASI) in the S&P MidCap 400 effective prior to the opening of trading on Thursday, June 11. S&P 500 & 100 constituent Danaher Corp. (NYSE: DHR) is acquiring Masimo 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
June 11, 2026	S&P MidCap 400		Addition	Sirius XM Holdings	SIRI	Communication Services
June 11, 2026	S&P MidCap 400		Deletion	Masimo	MASI	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.

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:

S&P Dow Jones Indices
index_services@spglobal.com

Media Inquiries
spdji.comms@spglobal.com

View original content:https://www.prnewswire.com/news-releases/sirius-xm-holdings-set-to-join-sp-midcap-400-302794483.html

SOURCE S&P Dow Jones Indices

FAQ

What change is S&P making to the S&P MidCap 400 on June 11, 2026?

S&P Dow Jones Indices will add Sirius XM Holdings and remove Masimo from the S&P MidCap 400 on June 11, 2026. According to S&P Dow Jones Indices, the reshuffle becomes effective before trading opens on that Thursday for index tracking and benchmark purposes.

When will Sirius XM Holdings (NASD: SIRI) be added to the S&P MidCap 400 index?

Sirius XM Holdings will be added to the S&P MidCap 400 before the market opens on Thursday, June 11, 2026. According to S&P Dow Jones Indices, Sirius XM will enter the index’s Communication Services sector on that effective date.

Why is Masimo (NASD: MASI) being removed from the S&P MidCap 400 in June 2026?

Masimo is being removed from the S&P MidCap 400 because Danaher is acquiring the company, pending final conditions. According to S&P Dow Jones Indices, Masimo’s deletion from the index will take effect before trading begins on June 11, 2026.

How is Danaher (NYSE: DHR) involved in the S&P MidCap 400 changes announced for June 2026?

Danaher is acquiring Masimo, which triggers Masimo’s removal from the S&P MidCap 400 index. According to S&P Dow Jones Indices, Danaher is an S&P 500 and S&P 100 member, and the Masimo transaction is expected to close after remaining conditions are satisfied.

What sector classifications apply to Sirius XM and Masimo in the June 11, 2026 S&P MidCap 400 update?

Sirius XM will join the S&P MidCap 400 as a Communication Services company, while Masimo exits from the Health Care sector. According to S&P Dow Jones Indices, both changes occur before the opening of trading on June 11, 2026.