Company: WBS-PG
Filing Date: 2025-09-05
Form Type: 424B5
Source: 0001193125-25-197211
Chunk: 76

Company: WEBSTER FINANCIAL CORP
Filing Date: 2025-09-05
Form: 424B5
Chunk 76
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 charge-offs; |

| • |     | changes in estimates of future reserve requirements based upon periodic review under relevant regulatory and 
 accounting requirements;                                                                                     |

| • |     | the effect of changes in accounting policies and practices applicable to us, including impacts of recently 
 adopted accounting guidance;                                                                               |

| • |     | our inability to remediate the material weaknesses in our internal control related to ineffective information 
 technology general controls;                                                                                  |

| • |     | legal and regulatory developments, including the resolution of legal proceedings or regulatory or other 
 governmental inquiries, and the results of regulatory examinations or reviews; and                      |

| • |     | our ability to appropriately address any environmental, social, governmental, and sustainability concerns that 
 may arise from our business activities.                                                                        |

Some of these and other factors are discussed in our annual and quarterly reports previously filed with the SEC. These factors could have an adverse impact on our financial position and our results of operations. All forward-looking statements in this prospectus speak only as of the date they are made. Factors or events that could cause the Company’s actual results to differ may emerge from time to time, and it is not possible for the Company to predict all of them. The Company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments, or otherwise, except as may be required by federal securities laws. In light of these risks, uncertainties and assumptions, the forward-looking events discussed in this prospectus or in the incorporated documents might not occur, and you should not put undue reliance on any forward-looking statements. 4

WEBSTER FINANCIAL CORPORATION

Webster Financial Corporation is a bank holding company and financial holding company under the Bank Holding Company Act of 1956, as amended (the
“BHC Act”), incorporated under the laws of Delaware in 1986, and headquartered in Stamford, Connecticut. Webster Bank, National Association (“Webster Bank”), along with HSA Bank, a division of Webster Bank
(“HSA Bank”), is a leading commercial bank in the Northeast that delivers a wide range of digital and traditional financial solutions to businesses, individuals, families, and partners across its three differentiated lines of
business: Commercial Banking, HSA Bank, and Consumer Banking. While our core footprint spans from New York to Rhode Island and Massachusetts, certain of our businesses operate in extended geographies. HSA Bank is one of the largest providers of
employee benefit solutions in the United States, which includes health savings accounts, health reimbursement