Solaris Energy Infrastructure Set to Join S&P SmallCap 600

Rhea-AI Summary

Solaris Energy Infrastructure (NYSE: SEI) will join the S&P SmallCap 600, replacing Catalyst Pharmaceuticals (NASD: CPRX), effective before the market opens on July 15, 2026. Catalyst is being removed as Angelini Pharma is acquiring the company, subject to final closing conditions.

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

Positive

• SEI added to S&P SmallCap 600 effective July 15, 2026
• Energy sector representation in S&P SmallCap 600 via Solaris Energy Infrastructure

Negative

• None.

What This Means

The announcement that Solaris will join, and Catalyst will leave, the S&P SmallCap 600 follows stock...

Analysis

The announcement that Solaris will join, and Catalyst will leave, the S&P SmallCap 600 follows stockholder approval of Catalyst’s $31.50-per-share Angelini acquisition. With the deal well advanced, investors may focus on closing timing and any remaining regulatory conditions.

Key Figures

Index change effective date: July 15, 2026

1 metrics

Index change effective date July 15, 2026 S&P SmallCap 600 addition of Solaris and deletion of Catalyst

Historical Context

5 past events · Latest: Jun 30 (Positive)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Jun 30	Phase 1 data	Positive	-0.1%	Reported favorable vamorolone Phase 1 data with limited immunosuppressive activity at clinical doses.
May 11	Q1 2026 earnings	Positive	-0.0%	Posted profitable Q1 with $149.3M net product revenue and strong cash position.
May 07	Call cancellation	Negative	-0.1%	Canceled Q1 earnings call due to pending Angelini acquisition, removing live Q&A session.
May 07	Patent settlement	Positive	+2.1%	Settled FIRDAPSE patent litigation, delaying potential U.S. generics until January 2035 if approved.
Apr 28	Earnings date set	Neutral	+0.6%	Announced schedule to release and discuss Q1 2026 financial results in mid-May.

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

Pattern Detected

Recent news, including strong earnings, clinical data and M&A milestones, has produced mostly small price moves, with a mix of aligned and divergent reactions to fundamentally positive updates.

Regulatory & Risk Context

Short Interest: 6.88%

Short Interest

6.88% of float

0% 15% 30%+

low as of 2026-06-15 Days to cover: 5.48

Reported short interest indicates relatively low bearish positioning, implying limited short-squeeze potential but also less short-covering support if volatility increases around merger or index-related flows.

Key Terms

s&p smallcap 600, gics sector

2 terms

s&p smallcap 600 financial

"will replace Catalyst Pharmaceuticals Inc. (NASD: CPRX) in the S&P SmallCap 600 effective"

A stock market index made up of 600 small-cap U.S. companies chosen to represent the performance of smaller publicly traded firms. It matters to investors because it acts like a temperature gauge for the small-company segment of the market, serving as a benchmark for fund managers, a basis for index funds and ETFs, and a way to compare returns and risk when building a diversified portfolio.

gics sector financial

"Ticker | GICS Sector -------------------------------------------------------------------------- July 15, 2026"

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. How Rhea-AI works. Not financial advice.

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NEW YORK, July 9, 2026 /PRNewswire/ -- Solaris Energy Infrastructure Inc. (NYSE: SEI) will replace Catalyst Pharmaceuticals Inc. (NASD: CPRX) in the S&P SmallCap 600 effective prior to the opening of trading on Wednesday, July 15. Angelini Pharma S.p.A. is acquiring Catalyst Pharmaceuticals in a deal expected to close 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
July 15, 2026	S&P SmallCap 600	Addition		Solaris Energy Infrastructure	SEI	Energy
July 15, 2026	S&P SmallCap 600	Deletion		Catalyst Pharmaceuticals	CPRX	Health Care

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SOURCE S&P Dow Jones Indices

FAQ

What change is occurring for Solaris Energy Infrastructure (NYSE: SEI) on July 15, 2026?

Solaris Energy Infrastructure will be added to the S&P SmallCap 600 index before trading opens on July 15, 2026. According to S&P Dow Jones Indices, SEI will replace Catalyst Pharmaceuticals in the benchmark.

Why is Catalyst Pharmaceuticals (NASDAQ: CPRX) being removed from the S&P SmallCap 600?

Catalyst Pharmaceuticals will be deleted from the S&P SmallCap 600 on July 15, 2026. According to S&P Dow Jones Indices, this follows Catalyst’s planned acquisition by Angelini Pharma, pending final closing conditions.

Which index will include Solaris Energy Infrastructure (SEI) after July 15, 2026?

Solaris Energy Infrastructure will be included in the S&P SmallCap 600 index. According to S&P Dow Jones Indices, SEI will join the index as an Energy sector constituent effective prior to the market open on July 15, 2026.

What sector classification will SEI have in the S&P SmallCap 600 index?

Solaris Energy Infrastructure will be classified in the Energy sector within the S&P SmallCap 600. According to S&P Dow Jones Indices, SEI joins the index as an Energy company, replacing Health Care company Catalyst Pharmaceuticals.

When does the replacement of CPRX by SEI in the S&P SmallCap 600 take effect?

The index replacement is effective before the opening of trading on July 15, 2026. According to S&P Dow Jones Indices, Solaris Energy Infrastructure will be added and Catalyst Pharmaceuticals deleted on that date.