☒QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIESEXCHANGE ACT OF 1934 For the quarterly period endedMarch 31, 2026OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIESEXCHANGE ACT OF 1934 For the transition period fromtoCommission File Number 001-40620BUILDERS FIRSTSOURCE, INC. (Exact name of registrant as specified in its charter) 52-2084569(I.R.S. EmployerIdentification No.) Delaware(State or other jurisdiction ofincorporation or organization) 6031 Connection Drive, Suite 400Irving, Texas(Address of principal executive offices) (214) 880-3500(Registrant’s telephone number, including area code) Name of Each Exchange on Which RegisteredNew York Stock ExchangeNYSETexas Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of theSecurities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to filesuch reports), and (2) has been subject to such filing requirements for the past 90 days.Yes☒No☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to besubmitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorterperiod that the registrant was required to submit such files).Yes☒No☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, asmaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,”“smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. Large accelerated filer☒Non-accelerated filer☐Emerging growth company☐If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐ Indicate by check mark whether the registrant is a shell company (as defined by Rule 12b-2 of the Exchange Act).Yes☐No The number of shares of the issuer’s common stock, par value $0.01, outstanding as of April 24, 2026, was 107,559,876. BUILDERS FIRSTSOURCE, INC. Index to Form 10-Q PART I — FINANCIAL INFORMATIONFinancial Statements (Unaudited) 3Item 1.3Condensed Consolidated Statements of Operations (Unaudited) for the Three Months Ended March 31, 2026and 20253Condensed Consolidated Balance Sheets (Unaudited) as of March 31, 2026, and December 31, 20254Condensed Consolidated Statements of Cash Flows (Unaudited) for the Three Months ended March 31, 2026and 20255Condensed Consolidated Statements of Changes in Stockholders’ Equity (Unaudited) for the Three MonthsEnded March 31, 2026 and 20256Notes to Condensed Consolidated Financial Statements (Unaudited)7Item 2.Management’s Discussion and Analysis of Financial Condition and Results of Operations14Item 3.Quantitative and Qualitative Disclosures About Market Risk18Item 4.Controls and Procedures18PART II — OTHER INFORMATION19Item 1.Legal Proceedings19Item 1A.Risk Factors19Item 2.Unregistered Sales of Equity Securities and Use of Proceeds19Item 5.Other Information19Item 6.Exhibits20 PART I — FINANCIAL INFORMATION BUILDERS FIRSTSOURCE, INC. AND SUBSIDIARIESCONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS(Unaudited) BUILDERS FIRSTSOURCE, INC. AND SUBSIDIARIESCONDENSED CONSOLIDATED BALANCE SHEETS(Unaudited) BUILDERS FIRSTSOURCE, INC. AND SUBSIDIARIESCONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS(Unaudited) BUILDERS FIRSTSOURCE, INC. AND SUBSIDIARIESCONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY(Unaudited) (1)During the three months ended March 31, 2025, we repurchased and retired 0.1 million shares of our common stock for$12.8 million, inclusive of applicable fees and taxes, at an average price of $131.51 per share.(2)During the three months ended March 31, 2026, we repurchased and retired 3.3 million shares of our common stock for$302.9 million, inclusive of applicable fees and taxes, at an average price of $92.25 per share.(3)Amounts paid in excess of par are allocated to additional paid-in capital during periods in which retained earnings isdepleted. The accompanying notes are an integral part of these condensed consolidated financial statements. BUILDERS FIRSTSOURCE, INC. AND SUBSIDIARIESNOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS(Unaudited) 1. Basis of Presentation Builders FirstSource, Inc., a Delaware corporation formed in 1998, is a leading supplier of building materials, manufacturedcomponents and construction services to professional contractors, sub-contractors, and consumers. The Company operatesapproximately 570 locations in 43 states across the United States. In this quarterly report, references to the “Company,” “we,”“our,” “ours” or “us” refer to Builders FirstSource, Inc. and its cons