Exhibit 99.1

Allegro MicroSystems Reports Second Quarter 2026 Results

Sales Increased 14% Year-Over-Year to $214 Million

Manchester, NH, October 30, 2025 – Allegro MicroSystems, Inc. (“Allegro” or the “Company”) (Nasdaq: ALGM), a global leader in power and sensing semiconductor solutions for motion control and energy efficient systems, today announced financial results for its second quarter ended September 26, 2025.

“We delivered strong second quarter results, with sales of $214 million, up 14% year-over-year, and led by growth in both e-Mobility and Industrial & Other, increasing 21% and 23% year-over-year, respectively. Non-GAAP EPS was $0.13, increasing more than 60% year-over-year,” said Mike Doogue, President and CEO of Allegro. “We saw broad strength in second quarter Automotive sales with growth in e-Mobility and Other Auto, while data center delivered record sales to fuel year-over-year growth in Industrial. In addition to this strong financial performance, year-to-date design wins are well ahead of fiscal 2025, with second quarter wins led by e-Mobility and data center.”

Second Quarter Financial Highlights:

Business Outlook

For the third quarter of fiscal year 2026 ending December 26, 2025, the Company expects total net sales to be in the range of
$215 million to $225 million. At the midpoint of this range, it implies growth in net sales of 24% year-over-year.

The Company also estimates the following results on a non-GAAP basis:

Allegro has not provided a reconciliation of its third fiscal quarter outlook for non-GAAP Gross Margin, non-GAAP Operating Expenses, non-GAAP Interest Expense, and non-GAAP Diluted Earnings per Share because estimates of all of the reconciling items cannot be provided without unreasonable efforts. It is difficult to reasonably provide a forward-looking estimate between such forward-looking non-GAAP measures and the comparable forward-looking U.S. generally accepted accounting principles (“GAAP”) measures. Certain factors that are materially significant to Allegro’s ability to estimate these items are out of its control and/or cannot be reasonably predicted.

Earnings Webcast

A webcast will be held on Thursday, October 30, 2025 at 8:30 a.m., Eastern Time. Michael C. Doogue, President and Chief Executive Officer, and Derek P. D’Antilio, Executive Vice President and Chief Financial Officer, will discuss Allegro’s business and financial results.

The webcast will be available on the Investor Relations section of the Company’s website at investors.allegromicro.com. A recording of the webcast will be posted in the same location shortly after the call concludes and will be available for at least 90 days.

About Allegro MicroSystems

Allegro MicroSystems, Inc. is leveraging more than three decades of expertise in magnetic sensing and power ICs, to propel automotive, clean energy and industrial automation forward with solutions that enhance efficiency, performance and sustainability. Allegro’s commitment to quality drives transformation across industries, reinforcing our status as a pioneer in “automotive grade” technology and a partner in our customers’ success. For additional information, please visit https://www.allegromicro.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements, other than statements of historical facts, contained in this press release including statements regarding our future results of operations and financial position, business strategy, prospective products and the plans and objectives of management for future operations, including, among others, statements regarding the liquidity, growth and profitability strategies and factors affecting our business are forward-looking statements. These statements involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements.

Without limiting the foregoing, in some cases, you can identify forward-looking statements by terms such as “aim,” “may,” “will,” “should,” “expect,” “exploring,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “would,” “contemplate,” “believe,” “estimate,” “predict,” “potential,” “seek,” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. No forward-looking statement is a guarantee of future results, performance or achievements, and one should avoid placing undue reliance on such statements.

Forward-looking statements are based on our management’s current expectations, beliefs and assumptions and on information currently available to us. Such beliefs and assumptions may or may not prove to be correct. Additionally, such forward-looking statements are subject to a number of known and unknown risks, uncertainties and assumptions, and actual results may differ materially from those expressed or implied in the forward-looking statements due to various factors, including, but not limited to, those identified in Part II, Item 7. “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” and Part I, Item 1A. “Risk Factors” in our Annual Report on Form 10-K for the year ended March 28, 2025, as any such factors may be updated from time to time in our Quarterly Reports on Form 10-Q and our other filings with the Securities and Exchange Commission (the “SEC”). These risks and uncertainties include, but are not limited to: downturns or volatility in general economic conditions; our ability to compete effectively, expand our market share and increase our net sales and profitability; our reliance on a limited number of third-party semiconductor wafer fabrication facilities and suppliers of other materials; any failure to adjust purchase commitments and inventory management based on changing market conditions or customer demand; shifts in our product mix, customer mix or channel mix, which could negatively impact our gross margin; the cyclical nature of the semiconductor industry, including the analog segment in which we compete; any downturn or disruption in the automotive market or industry; our ability to successfully integrate the acquisition of other companies or technologies and products into our business; our ability to compensate for decreases in average selling prices of our products and increases in input costs; our ability to manage any sustained yield problems or other delays at our third-party wafer fabrication facilities or in the final assembly and test of our products; our ability to accurately predict our quarterly net sales and operating results and meet the expectations of investors; our dependence on manufacturing operations in the Philippines; our reliance on distributors to generate sales; events beyond our control impacting us, our key suppliers or our manufacturing partners; our ability to develop new product features or new products in a timely and cost-effective manner; our dependence on growth in the end markets that use our products and the impact that slowdowns in such growth could have on our financial results; the loss of one or more significant customers; our ability to identify, enter and expand in new markets, and to generate returns on such investments; uncertainties related to the design win process and our ability to recover design and development expenses and to generate timely or sufficient net sales or margins; changes in government trade policies, including the imposition of export restrictions and tariffs; our exposures to warranty claims, product liability claims and product recalls; our dependence on international customers and operations; the availability of rebates, tax credits and other financial incentives on end-user demands for certain products; risks, liabilities, costs and obligations related to governmental regulations and other legal obligations, including export/trade control, privacy, data protection, information security, cybersecurity, consumer protection, environmental and occupational health and safety, antitrust, anti-corruption and anti-bribery, product safety, environmental protection, employment matters and tax; the risk of unsolicited acquisition proposals; the volatility of currency exchange rates; our ability to raise capital to support our growth strategy; our indebtedness may limit our flexibility to operate our business; our ability to retain key and highly skilled personnel; the impact of restructuring activities on our business and operating results; our ability to protect our proprietary technology and inventions through patents or trade secrets; our ability to commercialize our products without infringing third-party intellectual property rights; disruptions or breaches of our information technology systems or confidential information or those of our third-party service providers; any failure to maintain effective internal control over financial reporting; changes in tax rates or the adoption of new tax legislation; the negative impacts of sustained inflation on our business; the risks presented by climate change; the risks related to ESG matters; and other events beyond our control.

Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties.

You should read this press release and the documents that we reference completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements. All forward-looking statements speak only as of the date of this press release, and except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements, whether as a result of any new information, future events, changed circumstances or otherwise.

This press release includes certain non-GAAP financial measures as defined by the SEC rules. These non-GAAP financial measures are provided in addition to, and not as a substitute for or superior to measures of, financial performance prepared in accordance with GAAP. There are a number of limitations related to the use of these non-GAAP financial measures versus their most directly comparable GAAP equivalents. For example, other companies may calculate non-GAAP financial measures differently or may use other measures to evaluate their performance, all of which could reduce the usefulness of the presented non-GAAP financial measures as tools for comparison.

This press release may not be reproduced, forwarded to any person or published, in whole or in part.

ALLEGRO MICROSYSTEMS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except share and per share amounts)

(Unaudited)

Supplemental Schedule of Total Net Sales

The following table summarizes total net sales by market within the Company’s unaudited condensed consolidated statements of operations:

ALLEGRO MICROSYSTEMS, INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands)

ALLEGRO MICROSYSTEMS, INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

(Unaudited)

Non-GAAP Financial Measures

In addition to the measures presented in our condensed consolidated financial statements, we regularly review other measures, defined as non-GAAP financial measures by the SEC, to evaluate our business, measure our performance, identify trends, prepare financial forecasts and make strategic decisions. The key measures we consider are non-GAAP Gross Profit, non-GAAP Gross Margin, non-GAAP Operating Expenses, non-GAAP Operating Income, non-GAAP Operating Margin, EBITDA, Adjusted EBITDA, Adjusted EBITDA margin, non-GAAP Profit before Tax, non-GAAP Income Tax Provision, non-GAAP Effective Tax Rate, non-GAAP Net Income Attributable to Allegro MicroSystems, Inc, non-GAAP Basic and Diluted Earnings per Share, non-GAAP Free Cash Flow, and non-GAAP Free Cash Flow as a percentage of net sales (collectively, the “Non-GAAP Financial Measures”). These Non-GAAP Financial Measures provide supplemental information regarding our operating performance on a non-GAAP basis that excludes certain gains, losses and charges of a non-cash nature or that occur relatively infrequently and/or that management considers to be unrelated to our core operations, and in the case of non-GAAP Income Tax Provision, management believes that this non-GAAP measure of income taxes provides it with the ability to evaluate the non-GAAP Income Tax Provision across different reporting periods on a consistent basis, independent of special items and discrete items, which may vary in size and frequency. These Non-GAAP Financial Measures are used by both management and our board of directors, together with the comparable GAAP information, in evaluating our current performance and planning our future business activities.

The Non-GAAP Financial Measures are supplemental measures of our performance that are neither required by, nor presented in accordance with, GAAP. These Non-GAAP Financial Measures should not be considered as substitutes for GAAP financial measures, such as gross profit, gross margin, net income or any other performance measures derived in accordance with GAAP. Also, in the future we may incur expenses or charges, such as those being adjusted in the calculation of these Non-GAAP Financial Measures. Our presentation of these Non-GAAP Financial Measures should not be construed as an inference that future results will be unaffected by unusual or nonrecurring items. These Non-GAAP Financial Measures exclude costs related to acquisition and related integration expenses, amortization of acquired intangible assets, stock-based compensation, restructuring actions, related-party activities and other non-operational costs.

Non-GAAP Income Tax Provision

In calculating the non-GAAP Income Tax Provision, we adjust for the tax effect of adjustments to GAAP results which represents the estimated income tax effect of the adjustments to non-GAAP Profit before Tax described below. We also adjust for any discrete tax items and the impact of non-recurring tax law changes to ensure the non-GAAP Income Tax Rate (“NG ETR”) reflects future operations.

Our fiscal year 2026 and 2027 NG ETR excludes the impact of the 2025 One Big Beautiful Bill Act’s one-time research and development amortization election which accelerates the amortization of previously capitalized domestic research and development over a two-year period. The NG ETR is applied to non-GAAP Profit before Tax to arrive at the tax effect of adjustments to GAAP results.