Amentum Holdings, Inc. (AMTM)
AMTM moved a median of +0.08% 30 minutes after news, and -0.26% by the close. How AMTM actually reacts to news — the realized, point-in-time move the market made, measured across 120 labeled events over the last three years with zero look-ahead.
AMTM’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | +0.18% | 57% | 119 |
| 30-min | +0.08% | 54% | 119 |
| 60-min | +0.04% | 51% | 119 |
| to close | -0.26% | 48% | 119 |
| Middle 50% of AMTM reactions | -0.87% to +1.38% |
|---|---|
| Median reaction (30-min) | +0.08% |
| Measured reactions | 120 |
Half of all Amentum Holdings, Inc. news events land between -0.87% and +1.38% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How AMTM reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 16 | -0.42% | 31% | -1.96% |
| Coverage initiations | 37 | +0.29% | 54% | 0.00% |
| Rating reiterations | 46 | -0.47% | 30% | -0.53% |
| Price-target raises | 14 | -0.77% | 21% | -0.64% |
Last 3 years, pulled 2026-09-21. Reaction = percent move vs. the price at the news timestamp. Counts and medians only. The same measurement runs across every name in the dataset. 2 further classes were observed with fewer than 10 measured events and are not published. See how AMTM ranks against every other measured name →
That’s how AMTM usually reacts — get an email when it moves on news →Email me when AMTM moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to AMTM's baseline. Nothing else.
Recent AMTM events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Amentum Opens Global Nuclear Headquarters in Oak Ridge, Tennessee | Press release | Business Wire | +0.37% | +1.21% | |
| Form 8-K Amentum Holdings, Inc. For: Sep 28 | SEC filing · Form 8-K | SEC EDGAR | +0.38% | +0.44% | |
| Amentum Joint Venture Secures Preferred Position for Major UK Nuclear Contract | Press release | Business Wire | +0.00% | -0.66% | |
| Amentum Selected for Projects to Upgrade and Protect the UK Energy Grid | Press release | Business Wire | -0.30% | -0.69% | |
| Amentum Wins $974M Center Maintenance, Operations, and Engineering Contract at NASA Langley Research Center | Press release | Business Wire | +0.57% | -1.90% | |
| Amentum to Support Critical Infrastructure and Platforms Under New Engineering Services Framework | Press release | Business Wire | -0.14% | +0.14% | |
| Amentum Joint Venture Selected for Australia Nuclear Submarine Shipyard Program | Press release | Business Wire | -0.90% | +1.95% | |
| Form 10-Q Amentum Holdings, Inc. For: Jul 03 | SEC filing · Form 10-Q | SEC EDGAR | +1.31% | +1.67% | |
| Westinghouse and Amentum Partner to Expand Delivery Capacity for APX Fleet Deployment | Press release | Business Wire | +2.64% | +4.41% | |
| Amentum Selected for the Department of Energy AI Data Center and Energy Generation Project | Press release | Business Wire | +1.13% | +1.98% | |
| Amentum to Host Third Quarter Fiscal Year 2026 Earnings Conference Call on August 11, 2026 | Press release | Business Wire | -0.49% | +1.19% | |
| Amentum Recognized as One of America’s Best Companies 2026 by TIME Magazine | Press release | Business Wire | +0.02% | +1.50% | |
| Amentum Wins NASA’S COSMOS Contract to Advance Spaceflight Mission Operations | Press release | Business Wire | -0.83% | +0.83% | |
| Amentum Secures $77M Contract to Modernize Defense Supply Chain Logistics in the Indo-Pacific Region with AI Tools | Press release | Business Wire | +0.36% | -2.54% | |
| Amentum Debuts on the Fortune 500 List | Press release | Business Wire | -0.87% | +0.65% | |
| Amentum Names Dr. Sam Nazari Chief AI Architect | Press release | Business Wire | -0.30% | -3.08% | |
| Form 10-Q Amentum Holdings, Inc. For: Apr 03 | SEC filing · Form 10-Q | SEC EDGAR | -2.08% | -5.70% | |
| Amentum Reports Second Quarter Fiscal Year 2026 Results and Reaffirms Full Year Guidance | Press release | Business Wire | -2.23% | -4.74% | |
| Form 8-K Amentum Holdings, Inc. For: May 11 | SEC filing · Form 8-K | SEC EDGAR | -2.23% | -4.74% | |
| Form 8-K Amentum Holdings, Inc. For: Apr 24 | SEC filing · Form 8-K | SEC EDGAR | +0.95% | -1.93% | |
| Amentum to Host Second Quarter Fiscal Year 2026 Earnings Conference Call on May 12, 2026 | Press release | Business Wire | -1.34% | -2.86% | |
| Amentum Appoints Joseph DeNardi as Senior Vice President and Head of Investor Relations | Press release | Business Wire | -0.20% | +0.13% | |
| Amentum Powers Ground Systems Operations for NASA’s Historic Artemis II Mission | Press release | Business Wire | -0.04% | +4.51% | |
| Amentum Secures $425 Million Contract to Support California’s Aerial Firefighting Operations | Press release | Business Wire | +0.77% | -1.04% | |
| Amentum-Led Joint Venture Secures $406 Million Contract as Owner’s Engineer for UK’s First Small Modular Reactors | Press release | Business Wire | -0.26% | -0.83% | |
| Amentum Expands Operations in Hawaii, Enhances Support for USINDOPACOM, and Launches the Center for Contested Logistics | Press release | Business Wire | -0.10% | +0.50% | |
| Amentum-led Joint Venture selected for $112 Million Clean-up at Four European Nuclear Research Sites | Press release | Business Wire | -2.26% | -5.76% | |
| Amentum to Open New Global Headquarters Reflecting Growth and Expanded Mission | Press release | Business Wire | +1.77% | +4.98% | |
| Amentum Selected to Advance UK Hypersonic Strike Capabilities | Press release | Business Wire | -0.88% | -2.25% | |
| Form 10-Q Amentum Holdings, Inc. For: Jan 02 | SEC filing · Form 10-Q | SEC EDGAR | +3.65% | -0.28% | |
| Form 8-K Amentum Holdings, Inc. For: Feb 06 | SEC filing · Form 8-K | SEC EDGAR | -1.07% | -3.58% | |
| Amentum Reports First Quarter Fiscal Year 2026 Results and Reaffirms Full Year Guidance | Press release | Business Wire | +3.65% | -0.28% | |
| Form 8-K Amentum Holdings, Inc. For: Feb 09 | SEC filing · Form 8-K | SEC EDGAR | +3.65% | -0.28% | |
| Amentum Expands UK Nuclear Energy Specialist Services Portfolio with $730 Million Major Contracts Win | Press release | Business Wire | +1.09% | +1.23% | |
| Amentum-led Consortium Wins $207 Million Contract from Dutch Government for New Nuclear Program | Press release | Business Wire | +0.16% | +1.60% | |
| Amentum and Rolls-Royce SMR Partner on Building First Small Modular Reactors in the UK and Czech Republic | Press release | Business Wire | +0.75% | -0.26% | |
| Amentum Leads Successful Artemis II Rollout in Critical Preparation Phase of NASA Launch | Press release | Business Wire | +0.75% | -0.26% | |
| Amentum to Host First Quarter Fiscal Year 2026 Earnings Conference Call on February 10, 2026 | Press release | Business Wire | -0.03% | -0.29% | |
| Amentum Delivers Advanced Engineering for Key Artemis II Launch Rehearsal | Press release | Business Wire | +0.44% | -1.28% | |
| Form ARS Amentum Holdings, Inc. For: Oct 03 | SEC filing · Form ARS | SEC EDGAR | +1.62% | +1.81% | |
| Form DEF 14A Amentum Holdings, Inc. For: Feb 06 | SEC filing · Form DEF | SEC EDGAR | +1.62% | +1.81% | |
| Form DEFA14A Amentum Holdings, Inc. | SEC filing · Form DEFA14A | SEC EDGAR | +1.62% | +1.81% | |
| Amentum Wins Defense Threat Reduction Agency (DTRA) Prime Contract | Press release | Business Wire | -0.37% | +1.55% | |
| Amentum Wins $120 Million DISA Computer Processing Contract | Press release | Business Wire | +0.70% | +1.44% | |
| Form 10-K Amentum Holdings, Inc. For: Oct 03 | SEC filing · Form 10-K | SEC EDGAR | -1.08% | -4.06% | |
| Amentum Reports Strong Fourth Quarter and Fiscal Year 2025 Results | Press release | Business Wire | +6.90% | +7.22% | |
| Form 8-K Amentum Holdings, Inc. For: Nov 24 | SEC filing · Form 8-K | SEC EDGAR | +6.90% | +7.22% | |
| Amentum Wins U.S. Air Force Contract Worth up to $995M to Modernize the MQ-9 Unmanned Aerial System | Press release | Business Wire | +0.30% | -2.17% | |
| Amentum Wins Prime Positions on Multi-billion Pound Sellafield Decommissioning Framework | Press release | Business Wire | -0.60% | +0.85% | |
| Amentum to Host Fourth Quarter and Full Fiscal Year 2025 Earnings Conference Call on November 25, 2025 | Press release | Business Wire | +0.42% | +2.84% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the AMTM section they belong to.
Where else AMTM is measured.
AMTM earnings → · Analyst actions → · SEC filings →
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How the numbers are made.
How is Amentum Holdings, Inc.'s median reaction calculated?
Every labeled AMTM news event is measured from its own timestamp: the last trade before the news is the base price, and the move is read at fixed horizons — 30 minutes of trading, then the close. The median across 120 events is what this page reports. Point-in-time, zero look-ahead: no event borrows information from a later one.
What counts as a positive reaction?
Any event whose price move is above zero at the horizon, relative to the last trade before the news timestamp. 54% of AMTM's measured events are up at 30 minutes; the rest close the window flat or negative.
How often is this page updated?
The news table refreshes automatically as new events are labeled and priced. The reaction medians are re-pulled in batches from the dataset — the figures here are as of 2026-09-21.
Does AMTM's past reaction predict its next one?
No. These are realized facts about past events, not forecasts. They describe a distribution — they say nothing certain about any future move.