Repligen Corporation 41 Seyon Street Building #1, Suite 100 Waltham, Massachusetts 02453 Repligen Reports First Quarter 2023 Financial Results and Updates Full Year 2023 Financial Guidance Reports first quarter revenue o

Repligen Corporation

Building #1, Suite 100

Waltham, Massachusetts 02453

Repligen Reports First

Quarter 2023 Financial Results

and Updates Full Year 2023 Financial Guidance

WALTHAM, Mass., May 2, 2023 Repligen Corporation (NASDAQ:RGEN), a life sciences company

focused on bioprocessing technology leadership, today reported financial results for its first fiscal quarter ended March 31, 2023. Provided in this press release are financial highlights for the quarter, updates to our financial guidance for

the year 2023 and access information for today s webcast and conference call.

Tony J. Hunt, President and Chief Executive Officer of Repligen said,

Given the challenging macro environment, I am very happy with our overall performance in the first quarter, with year-over-year base business growth of 7% at constant currency. In the quarter, we saw strong performance from our Chromatography

and Proteins franchises, while Filtration was down reflecting the predicted drop-off in COVID-related revenue. Strategically, we continue to build out our Fluid Management portfolio with the April

acquisition of FlexBiosys, adding single-use bags to our suite of products. As we move through the first half of 2023, our R&D team is poised to deliver four new products supporting our Systems,

Analytics and Filtration businesses. Overall, we continue to be bullish on the medium- to long-term growth in bioprocessing but expect 2023 to be a challenging year due to a slower recovery in order growth, especially in AsiaPac. We now expect 4% to

8% base business growth for the company.

Business and Financial Highlights

First Quarter and Year-to-Date 2023 Business Highlights

First Quarter 2023 Financial Highlights

GROSS PROFIT and GROSS MARGIN

INCOME FROM OPERATIONS

NET INCOME PER SHARE-Diluted (EARNINGS PER SHARE-Diluted)

All reconciliations of GAAP to adjusted

(non-GAAP) figures above, as well as EBITDA to adjusted EBITDA, are detailed in the reconciliation tables included later in this press release.

Financial Guidance for 2023

Our financial guidance for

the fiscal year 2023 is based on expectations for our existing business. This guidance includes the impact of our FlexBiosys acquisition and excludes the impact of potential additional acquisitions, and future fluctuations in foreign currency

Our non-GAAP guidance for the fiscal year 2023 excludes the following items:

Our non-GAAP guidance for the fiscal year 2023 includes:

All reconciliations of GAAP

to adjusted (non-GAAP) guidance are detailed in the tables included later in this press release.

Conference Call and Webcast Access

Repligen will host a

conference call and webcast today, May 2, 2023, at 8:30 a.m. ET, to discuss first quarter 2023 financial results, corporate developments and financial guidance for the year 2023. The conference call will be accessible by dialing toll-free (844)

274-3999 for domestic callers or (412) 317-5607 for international callers. No passcode is required for the live call. In addition, a webcast will be accessible via the

Investor Relations section of the Company s website. Both the conference call and webcast will be archived for a period of time following the live event. The replay dial-in numbers are (877) 344-7529 from the U.S., (855) 669-9658 from Canada and (412) 317-0088 for international callers. Replay listeners must provide the

Non-GAAP Measures of Financial Performance

To supplement our financial statements, which are presented on the basis of U.S. generally accepted accounting principles (GAAP), the following non-GAAP measures of financial performance are included in this release: revenue growth rate at constant currency; adjusted gross profit and adjusted gross margin; adjusted cost of sales; adjusted R&D expense;

adjusted SG&A expense; adjusted income from operations; adjusted net income; adjusted net income per share-diluted; earnings before interest, taxes, depreciation and amortization (EBITDA); and adjusted EBITDA. The Company provides organic

revenue growth rates, which exclude the impact of both foreign currency translation and the impact of acquisition revenue for current year periods that have no prior year comparable in order to facilitate a comparison of its current revenue

performance. The Company provides revenue growth rates at constant currency, which exclude the impact of foreign currency translation, in order to facilitate a comparison of its current revenue performance to its past revenue performance. To

calculate revenue growth rates in constant currency, the Company converts actual net sales from local currency to U.S. dollars using constant foreign currency exchange rates in the current and prior period.

The Company s non-GAAP financial results and/or non-GAAP guidance exclude

the impact of: acquisition and integration costs, intangible amortization costs, contingent consideration related to the Company s acquisitions, amortization of debt issuance costs related to Company s convertible debt, non-cash interest expense, and the related impact on tax of non-GAAP charges. These costs are excluded because management believes that such expenses do not have a direct

correlation to future business operations, nor do the resulting charges recorded accurately reflect the performance of our ongoing operations for the period in which such charges are recorded.

A reconciliation of GAAP to adjusted non-GAAP financial measures is included as an attachment to this press

release. When analyzing the Company s operating performance and guidance investors should not consider non-GAAP measures as substitutable for the comparable financial measures prepared in accordance with

About Repligen Corporation

Corporation is a global company that develops and commercializes highly innovative bioprocessing technologies and systems that enable efficiencies in the process of manufacturing biological drugs. We are inspiring advances in bioprocessing for the

customers we serve; primarily biopharmaceutical drug developers and contract development and manufacturing organizations (CDMOs) worldwide. Our focus areas are Filtration, Chromatography, Process Analytics, Fluid Management and Proteins. Our

corporate headquarters are located in Waltham, Massachusetts, with additional administrative and manufacturing operations worldwide. The majority of our manufacturing sites are located within the U.S. (California, Massachusetts, New Hampshire, New

LinkedIn and Twitter.

Forward-Looking Statement

The following constitutes a Safe Harbor statement under the Private Securities Litigation Reform Act of 1995: This press release contains

forward-looking statements, which are made pursuant to the safe harbor provisions of federal securities laws, including Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as

amended. Investors are cautioned that statements in this press release which are not strictly historical statements, including, without limitation, express or implied statements or guidance regarding current or future financial performance and

position, including our year 2023 financial guidance, cash and investment position, demand in the markets in which we operate, the expected performance of our business, the expected performance and success of our strategic partnerships , the

expected performance and integration of our acquired businesses (including our 2023 acquisition of FlexBiosys), expectations regarding manufacturing expenses, plans for gross margin expansion, our ability to continue to generate, and the magnitude

of, COVID-related revenue, and management s strategy, plans and objectives for operations or future acquisitions, product development and sales, selling, general and administrative expenditures, constitute forward-looking statements identified

by words like believe, expect, may, will, should, seek, anticipate, projected, estimated or could and similar expressions.

Forward-looking statements are neither historical facts nor assurances of future performance. Because forward-looking statements relate to the future, they are subject to a number of risks and uncertainties that could cause actual results to differ

materially from those anticipated, including, without limitation, risks associated with the following: the ongoing effect of the COVID-19 coronavirus pandemic, including mitigation efforts and economic

effects, on our business operations and the operations of our customers and suppliers, as well as on our revenues; our ability to successfully grow our bioprocessing business, including as a result of acquisition, commercialization or partnership

opportunities; our ability to develop and commercialize products and the market acceptance of our products; our ability to successfully integrate any acquired businesses (including FlexBiosys) into our business and achieve the expected benefits of

such acquisitions; reduced demand for our products that adversely impacts our future revenues, cash flows, results of operations and financial condition; our ability to compete with larger, better financed bioprocessing, pharmaceutical and

biotechnology companies; our ability to manage expenses; our compliance with all U.S. Food and Drug Administration and EMEA regulations; our volatile stock price; and other risks detailed in Repligen s Annual Report on Form 10-K for the year ended December 31, 2022 and in subsequently filed reports with the Securities and Exchange Commission (the Commission), including our Quarterly Reports on Form

10-Q and current reports on Form 8-K that we file with the Commission. Actual results may differ materially from those Repligen contemplated by these forward-looking

statements. Therefore, you should not rely on any of these forward-looking statements. These forward-looking statements reflect management s current views, expectations, and assumptions regarding the future of our business, future plans and

strategies, projections, anticipated events and trends, the economy and other future conditions, and are based only on information currently available to us. Repligen does not undertake to update, whether written or oral, any of these

forward-looking statements to reflect a change in its views or events or circumstances, whether as a result of new information, future development or otherwise, that occur after the date hereof except as required by law.

Global Head of Investor Relations

REPLIGEN CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(Unaudited, amounts in thousands, except share and per share data)

REPLIGEN CORPORATION

RECONCILIATION OF GAAP INCOME FROM OPERATIONS TO

NON-GAAP (ADJUSTED) INCOME FROM OPERATIONS

(Unaudited, amounts in thousands)

REPLIGEN CORPORATION

RECONCILIATION OF GAAP NET INCOME TO NON-GAAP (ADJUSTED) NET INCOME

(Unaudited, amounts in thousands)

REPLIGEN CORPORATION

RECONCILIATION OF GAAP NET INCOME PER SHARE TO

NON-GAAP (ADJUSTED) NET INCOME PER SHARE

Totals may not add due to

REPLIGEN CORPORATION

RECONCILIATION OF GAAP NET INCOME TO ADJUSTED EBITDA

(Unaudited, amounts in thousands)

REPLIGEN CORPORATION

RECONCILIATION OF GAAP COST OF SALES TO NON-GAAP (ADJUSTED) COST OF SALES

(Unaudited, amounts in thousands)

REPLIGEN CORPORATION

RECONCILIATION OF GAAP R&D EXPENSE TO NON-GAAP (ADJUSTED) R&D EXPENSE