July S&P SmallCap 600 additions lifted Solaris Energy Infrastructure, Five9, Karman Holdings, Construction Partners, and Centrus Energy.
Sectors & Industries
August 4, 2026
Table of Contents
August 4, 2026
Several companies were added to the S&P SmallCap 600 in July 2026, with the strongest initial stock reactions coming from Solaris Energy Infrastructure, Five9, Karman Holdings, Construction Partners, and Centrus Energy.
The additions covered several sectors, including energy, industrials, information technology, and food processing. Most of the index changes were tied to mergers, acquisitions, spin-offs, or companies moving between S&P indexes.
Solaris Energy Infrastructure Inc. (NYSE: SEI) was added to the S&P SmallCap 600 in July.
Key data:
Price: $55.52
Date: July 9, 2026
Session: After-hours
Initial impact: +7.995%
Follow-through move shown: +4.849%
52-week range: $24.57 to $86.19
Solaris Energy Infrastructure provides energy infrastructure and equipment solutions, including systems used in power, logistics, and oilfield operations.
The stock had the strongest initial reaction among the July additions tracked in the dataset.
S&P Dow Jones Indices said Solaris Energy Infrastructure would replace Catalyst Pharmaceuticals in the S&P SmallCap 600, effective before the open on July 15.
Five9, Inc. (NASDAQ: FIVN) was added to the S&P SmallCap 600 after Two Harbors Investment was removed from the index.
Key data:
Price: $28.95
Date: July 29, 2026
Session: After-hours
Initial impact: +5.234%
Follow-through move shown: +0.000%
52-week range: $13.29 to $28.86
Five9 provides cloud contact center software, customer experience tools, AI automation, workforce engagement products, and enterprise communication solutions.
S&P Dow Jones Indices said Five9 would replace Two Harbors Investment in the S&P SmallCap 600, effective before the open on August 3. CrossCountry Mortgage was acquiring Two Harbors in a deal expected to close soon.
Karman Holdings Inc. (NYSE: KRMN) was added to the S&P SmallCap 600 in July.
Key data:
Price: $50.44
Date: July 14, 2026
Session: After-hours
Initial impact: +4.756%
Follow-through move shown: +6.437%
52-week range: $43.681 to $118.38
Karman Holdings operates in the industrial and aerospace supply chain, serving markets tied to defense, space, and advanced manufacturing.
S&P Dow Jones Indices said Karman Holdings would replace BrightSpring Health Services in the S&P SmallCap 600, effective before the open on July 17.
The addition came as BrightSpring moved into the S&P MidCap 400.
Construction Partners, Inc. (NASDAQ: ROAD) was added to the S&P SmallCap 600 in July.
Key data:
Price: $108.12
Date: July 16, 2026
Session: After-hours
Initial impact: +4.615%
Follow-through move shown: +2.012%
52-week range: $93.22 to $151.00
Construction Partners is an infrastructure and road construction company focused on asphalt production, highway construction, paving, site development, and related civil infrastructure services.
S&P Dow Jones Indices said Construction Partners would replace Molina Healthcare in the S&P SmallCap 600, effective before the open on July 22.
Molina Healthcare moved to the S&P MidCap 400 as part of the same index reshuffle.
Centrus Energy Corp. (NYSE: LEU) was added to the S&P SmallCap 600 in July.
Key data:
Price: $184.76
Date: July 2, 2026
Session: After-hours
Initial impact: +4.425%
Follow-through move shown: +0.000%
52-week range: $142.13 to $464.25
Centrus Energy supplies nuclear fuel and related services, including uranium enrichment and advanced nuclear fuel development.
S&P Dow Jones Indices said Centrus Energy would replace Whitestone REIT in the S&P SmallCap 600, effective before the open on July 14.
Whitestone REIT was being acquired by Ares Management.
Tutor Perini Corporation (NYSE: TPC) was added to the S&P SmallCap 600 in July.
Key data:
Price: $85.73
Date: July 20, 2026
Session: After-hours
Initial impact: +2.364%
Follow-through move shown: +7.748%
52-week range: $45.56 to $100.00
Tutor Perini is a construction and civil infrastructure company involved in building, transportation, industrial, and specialty contracting projects.
S&P Dow Jones Indices said Tutor Perini would replace Krystal Biotech in the S&P SmallCap 600, effective before the open on July 24.
Krystal Biotech moved to the S&P MidCap 400.
While Tutor Perini’s initial reaction was smaller than several other additions, it had the strongest follow-through move shown in the dataset.
Midera Food Processing, Inc. (NASDAQ: MFP) was added to the S&P SmallCap 600 in July.
Key data:
Price: $47.29
Date: July 2, 2026
Session: Intraday
Initial impact: -1.376%
Follow-through move shown: +0.000%
52-week range: $21.00 to $200.00
Midera Food Processing was added after being spun off from The Middleby Corporation.
S&P Dow Jones Indices said Midera Food Processing would replace Redwood Trust in the S&P SmallCap 600, effective before the open on July 8.
Redwood Trust was removed because it was no longer representative of the small-cap market space.
Midera was the only July SmallCap 600 addition in the dataset with a negative initial stock reaction.
The July S&P SmallCap 600 additions showed several themes.
First, index inclusion continued to act as a short-term catalyst for many small-cap stocks.
Solaris Energy Infrastructure, Five9, Karman Holdings, Construction Partners, Centrus Energy, and Tutor Perini all showed positive initial reactions.
Second, industrials were heavily represented.
Tutor Perini, Construction Partners, Karman Holdings, and Midera Food Processing all came from industrial or industrial-adjacent categories.
Third, energy also stood out.
Solaris Energy Infrastructure had the strongest initial reaction, while Centrus Energy also traded higher after its addition announcement.
Fourth, not every addition produced a positive reaction.
Midera Food Processing declined after its index addition announcement, showing that index inclusion alone does not guarantee a positive stock move.
S&P SmallCap 600 additions can create short-term demand because index funds and benchmarked investors may need to adjust holdings.
That can lead to fast stock moves around announcement dates and effective dates.
But the longer-term impact depends on the company’s fundamentals, earnings growth, sector trends, liquidity, and investor demand after the index rebalance is complete.
July’s strongest reactions came from Solaris Energy Infrastructure, Five9, Karman Holdings, Construction Partners, and Centrus Energy, while Tutor Perini showed the strongest follow-through move in the dataset.
Platforms like LevelFields track S&P 600 additions and removals in real timealongside, activist investor stake, layoffs, earnings, strategic events, and dividends, helping investors identify when index inclusion is acting as a short-term catalyst or confirming broader investor demand.
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