Tenable Holdings Set to Join S&P SmallCap 600

Rhea-AI Summary

Tenable Holdings (NASD: TENB) will be added to the S&P SmallCap 600, replacing Leggett & Platt (NYSE: LEG), effective prior to the open on August 31, 2026, according to S&P Dow Jones Indices. Leggett & Platt is being acquired by Somnigroup International (NYSE: SGI), a constituent of the S&P MidCap 400, in a transaction expected to close soon, subject to final conditions.

The index change will place Tenable in the Information Technology sector within the S&P SmallCap 600, while Leggett & Platt, classified in Consumer Discretionary, will be deleted from that index on the same effective date.

Positive

• Tenable added to S&P SmallCap 600 effective August 31, 2026
• Somnigroup acquiring Leggett & Platt, triggering index rebalancing

Negative

• Leggett & Platt removed from S&P SmallCap 600 on August 31, 2026

Market Context

BOX was moving up 1.8268942832946775% in the current momentum scanner, providing broader software co...

Analysis

BOX was moving up 1.8268942832946775% in the current momentum scanner, providing broader software context for Tenable’s index addition. The platform also recorded Net Selling by insiders, a risk factor to monitor alongside index-status changes.

Key Figures

Effective Date: August 31, 2026

1 metrics

Effective Date August 31, 2026 S&P SmallCap 600 addition before market open

Historical Context

5 past events · Latest: Aug 26 (Positive)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Aug 26	Cybersecurity research	Positive	+2.6%	Joint research identified vendor-ecosystem targeting and reported 79% exposure-runtime alignment.
Aug 10	Investor conference	Positive	+0.9%	Leadership presentations at two scheduled investor conferences preceded a 0.88% reaction.
Aug 04	AI platform launch	Positive	+2.8%	Company launched an open-source AI-agent exchange with more than 50 components available.
Aug 04	AI security expansion	Positive	+2.8%	AI security coverage expanded across major platforms after 457 million issues detected.
Jul 29	Q2 earnings report	Positive	+3.4%	Q2 revenue exceeded expectations, and management raised the full-year outlook.

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

Pattern Detected

Recent Tenable news events in the platform record all had positive 24-hour price reactions.

Key Terms

s&p smallcap 600, gics sector

2 terms

s&p smallcap 600 financial

"Tenable Holdings Inc. will replace Leggett & Platt Inc. in the S&P SmallCap 600"

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

"Company Name | 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. How Rhea-AI works. Not financial advice.

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NEW YORK, Aug. 26, 2026 /PRNewswire/ -- Tenable Holdings Inc. (NASD: TENB) will replace Leggett & Platt Inc. (NYSE: LEG) in the S&P SmallCap 600 effective prior to the opening of trading on Monday, August 31. S&P MidCap 400 constituent Somnigroup International Inc. (NYSE: SGI) is acquiring Leggett & Platt in a deal expected to be completed 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
Aug 31, 2026	S&P SmallCap 600	Addition		Tenable Holdings	TENB	Information Technology
Aug 31, 2026	S&P SmallCap 600	Deletion		Leggett & Platt	LEG	Consumer Discretionary

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SOURCE S&P Dow Jones Indices

FAQ

When will Tenable Holdings (TENB) join the S&P SmallCap 600 index?

Tenable Holdings will join the S&P SmallCap 600 before trading opens on August 31, 2026. According to S&P Dow Jones Indices, Tenable will be added as an Information Technology company during this index rebalancing, replacing Leggett & Platt.

Which company is Tenable Holdings (TENB) replacing in the S&P SmallCap 600 on August 31, 2026?

Tenable Holdings will replace Leggett & Platt (LEG) in the S&P SmallCap 600 on August 31, 2026. According to S&P Dow Jones Indices, Leggett & Platt will be deleted from the index due to its pending acquisition.

Why is Leggett & Platt (LEG) being removed from the S&P SmallCap 600 index?

Leggett & Platt is being removed because it is being acquired by Somnigroup International (SGI). According to S&P Dow Jones Indices, this acquisition, expected to close soon pending final conditions, triggers Leggett & Platt’s deletion from the S&P SmallCap 600.

What sector classification will Tenable Holdings (TENB) have in the S&P SmallCap 600?

Tenable Holdings will be classified in the Information Technology sector within the S&P SmallCap 600. According to S&P Dow Jones Indices, this sector assignment reflects Tenable’s business profile as it enters the index on August 31, 2026.

How does Somnigroup International (SGI) factor into the S&P index changes involving LEG and TENB?

Somnigroup International, an S&P MidCap 400 constituent, is acquiring Leggett & Platt. According to S&P Dow Jones Indices, this pending acquisition leads to Leggett & Platt’s removal from the S&P SmallCap 600 and the simultaneous addition of Tenable Holdings.

Will Somnigroup International (SGI) change indexes after acquiring Leggett & Platt (LEG)?

The announcement does not state any index change for Somnigroup International. According to S&P Dow Jones Indices, SGI remains an S&P MidCap 400 constituent while acquiring Leggett & Platt, which is being removed from the S&P SmallCap 600.