Aclaris Therapeutics Added to the NASDAQ Biotechnology Index (NBI)

Rhea-AI Summary

Aclaris Therapeutics (NASDAQ: ACRS) was added to the Nasdaq Biotechnology Index (NBI), effective at the close of trading on December 19, 2025. The NBI tracks securities classified as biotechnology or pharmaceutical under the Industry Classification Benchmark and uses a modified capitalization-weighted methodology.

The company met NBI eligibility requirements, including minimum market capitalization, average daily trading volume and public company seasoning; the index is evaluated annually each December.

Positive

• Added to Nasdaq Biotechnology Index effective December 19, 2025
• Met NBI eligibility requirements including market cap, volume and seasoning

Negative

• None.

News Market Reaction – ACRS

-2.23%

-2.23% News Effect

On the day this news was published, ACRS declined 2.23%, reflecting a moderate negative market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

This announcement adds Aclaris to the Nasdaq Biotechnology Index as of Dec 19, 2025, reflecting that...

Analysis

This announcement adds Aclaris to the Nasdaq Biotechnology Index as of Dec 19, 2025, reflecting that it meets requirements for market capitalization, trading volume, and listing history. Coming after months of R&D, conference, and earnings updates, the news highlights growing market recognition rather than new clinical data. Investors may watch how index-related demand interacts with its existing uptrend above the $1.81 200-day moving average and ongoing pipeline milestones.

Historical Context

5 past events · Latest: Nov 25 (Neutral)

Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Nov 25	Conference participation	Neutral	-0.7%	Announcement of CEO participation in Piper Sandler healthcare conference fireside chat.
Nov 06	Earnings and update	Neutral	+0.4%	Q3 2025 financial results and clinical pipeline update including ATI-2138 and bosakitug.
Oct 29	Conference schedule	Neutral	-2.1%	Planned participation in three November healthcare conferences with leadership presentations.
Sep 30	R&D Day announcement	Neutral	-1.0%	Announcement of 2025 R&D Day focusing on immuno-inflammatory pipeline progress.
Sep 09	Clinical data update	Positive	+2.4%	Late-breaking abstract and oral presentation of ATI-2138 Phase 2a results at EADV Congress.

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

Pattern Detected

Recent news has mostly been neutral-to-positive (conferences, R&D and data updates), yet three of the last five items saw negative next-day price moves, with more favorable reactions tied to clinical data updates.

Recent Company History

Over the last several months, Aclaris reported R&D and conference participation, a Q3 2025 earnings update, and Phase 2a data for ATI-2138. Events on Sep 09, 2025 and Nov 06, 2025 with clinical and financial updates coincided with modest positive moves, while multiple conference-related announcements around Sep–Nov 2025 saw small declines. Today’s inclusion in the Nasdaq Biotechnology Index adds an index-recognition milestone alongside its ongoing clinical and corporate activities.

Key Terms

Nasdaq Biotechnology Index, Industry Classification Benchmark, capitalization-weighted methodology

3 terms

Nasdaq Biotechnology Index financial

"announced it has been added to the Nasdaq Biotechnology Index (NASDAQ: NBI)"

A stock index that tracks the performance of biotechnology companies listed on the NASDAQ stock exchange, combining many firms into a single measure of the sector’s movement. Think of it as a thermometer or basket that shows whether biotech stocks are generally rising or falling; investors use it to gauge sector health, compare individual holdings against the industry, and as the basis for funds that let you invest in the whole group at once.

Industry Classification Benchmark technical

"classified as either biotechnology or pharmaceutical according to the Industry Classification Benchmark"

A standardized system that groups companies into industries and sectors based on their main business activities, like a library catalog that puts similar books together. It matters to investors because it enables fair comparisons between peers, guides portfolio construction and sector allocation, determines which stocks belong in industry indexes or ETFs, and helps track industry-level risks and performance trends.

capitalization-weighted methodology technical

"The NBI is evaluated annually in December and is calculated under a modified capitalization-weighted methodology"

A capitalization-weighted methodology is a way to build an index or portfolio where each company’s weight equals its total stock-market value, so bigger companies have bigger influence. For investors it matters because performance tracks larger firms more closely, which can make results less sensitive to small companies’ swings — like a playlist where hit songs play more often, shaping the overall listening experience.

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

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WAYNE, Pa., Dec. 19, 2025 (GLOBE NEWSWIRE) -- Aclaris Therapeutics, Inc. (NASDAQ: ACRS), a clinical-stage biopharmaceutical company focused on developing novel product candidates for immuno-inflammatory diseases, today announced it has been added to the Nasdaq Biotechnology Index (NASDAQ: NBI), effective at the close of trading today, December 19, 2025.

The NBI is designed to track the performance of a set of securities listed on The Nasdaq Stock Market^® that are classified as either biotechnology or pharmaceutical according to the Industry Classification Benchmark. Companies in the NBI must meet eligibility requirements, including minimum market capitalization, average daily trading volume and seasoning as a public company, among other criteria. The NBI is evaluated annually in December and is calculated under a modified capitalization-weighted methodology.

For more information about the Nasdaq Biotechnology Index, please visit this link.

About Aclaris Therapeutics, Inc.

Aclaris Therapeutics, Inc. is a clinical-stage biopharmaceutical company developing a pipeline of novel product candidates to address the needs of patients with immuno-inflammatory diseases who lack satisfactory treatment options. The company has a multi-stage portfolio of product candidates powered by a robust R&D engine. For additional information, please visit www.aclaristx.com and follow Aclaris on X (formerly Twitter) at @AclarisTx and on LinkedIn.

Aclaris Therapeutics Contact:

Will Roberts
Senior Vice President
Corporate Communications and Investor Relations
(484) 329-2125
wroberts@aclaristx.com

FAQ

What does Aclaris (ACRS) addition to the Nasdaq Biotechnology Index mean for investors?

Aclaris (ACRS) was added to the Nasdaq Biotechnology Index effective Dec 19, 2025, giving the stock index inclusion and potential increased visibility to institutional and passive investors.

When did ACRS officially join the Nasdaq Biotechnology Index (NBI)?

Aclaris (ACRS) was officially added to the NBI at the close of trading on December 19, 2025.

What eligibility criteria did Aclaris meet to join the NBI?

Aclaris met NBI eligibility requirements including minimum market capitalization, average daily trading volume, and public company seasoning.

How often is the Nasdaq Biotechnology Index (NBI) evaluated?

The Nasdaq Biotechnology Index is evaluated annually in December and is calculated under a modified capitalization-weighted methodology.

Will ACRS inclusion in the NBI change the index weighting method?

The index continues to be calculated under a modified capitalization-weighted methodology; Aclaris addition follows that existing methodology.

Where can investors find more information about the Nasdaq Biotechnology Index listing criteria?

For full details on NBI eligibility and methodology, refer to Nasdaq's published index documentation available on the Nasdaq website.