RBB Bancorp

In connection with the review of RBB Bancorp’s (the “Company”, “we”, “us” or “our”) interim financial statements for the three months ended September 30, 2023, the Company’s independent registered public accounting firm identified an adjustment to the Company’s noninterest income and net income during the interim period . The Company received a $5.0 million grant as a part of the Community Development Financial Institution Equitable Recovery Program award (the “Award”) during the interim period, which was previously recorded as noninterest income. The Company had previously announced in its quarterly earnings release that the Company’s noninterest income for the three months ended September 30, 2023 was $7.7 million, which included the full amount of the $5.0 million Award received. The Company subsequently determined that the income recognition should be deferred and not included in noninterest income for the interim period. As a result, the Company’s noninterest income for the three months ended September 30, 2023 was $2.8 million, and its net income for the interim period was $8.5 million instead of the $12.0 million previously announced in the Company’s quarterly earnings release. Management of the Company and the Company’s independent public accounting firm re-evaluated the Company’s internal control over financial reporting related to infrequent transactions such as the income recognition for the Award and concluded that a material weakness existed in that area. As a result, management of the Company determined that the Company’s internal control over financial reporting and disclosure controls and procedures were not effective as of September 30, 2023

RBB Bancorp (the “Company”) is unable to file its Annual Report on Form 10-K for the year ended December 31, 2022 (“Annual Report”) within the prescribed time period without unreasonable effort or expense due to circumstances related to the Company’s first-time adoption of Accounting Standards Update 2016-13 (Topic 326), “Measurement of Credit Losses on Financial Instruments,” commonly referenced as the Current Expected Credit Loss (“CECL”) model. The Company also needs additional time to complete the analysis and evaluate its internal controls over financial reporting related to its adoption of CECL. The Company also needs additional time for Crowe LLP (“Crowe”), its independent registered public accounting firm, to complete certain audit procedures related to the Company’s adoption of CECL, including its evaluation of the effectiveness of the Company’s internal controls over financial reporting. Notwithstanding the foregoing, the Company expects to file its Annual Report no later than March 31, 2023. The Company does not expect any changes to its financial results reported in its press release dated January 23, 2023. The Company has provided a copy of the foregoing disclosures to Crowe. Forward-Looking Statements This filing contains a number of forward-looking statements. Words such as "expect," "will," "working," and variations of such words and similar future or conditional expressions are intended to identify forward-looking statements. These forward-looking statements include, but are not limited to, statements regarding our beliefs and expectations relating to the filing of the Annual Report. These forward-looking statements are not guarantees of future results and are subject to a number of risks and uncertainties, many of which are difficult to predict and beyond our control

The Company is unable to file, without unreasonable effort and expense, its Form 10-Q for the quarterly period ended September 30, 2022 (the “Report”) as the Company recently appointed Crowe LLP ("Crowe") as our new independent registered public accounting firm ("CPA") on September 26, 2022. Crowe needs more time to complete the Sarbanes-Oxley Act ("SOX") control reviews with the Company, to complete its review of the interim financial statements and the Report and other matters. Notwithstanding the foregoing, the Company expect to file no later than November 30, 2022. The Company has provided a copy of the foregoing disclosures to Crowe. Forward-Looking Statements This filing contains a number of forward-looking statements. Words such as "expect," "will," "working," and variations of such words and similar future or conditional expressions are intended to identify forward-looking statements. These forward-looking statements include, but are not limited to, statements regarding our beliefs and expectations relating to the filing of the Form 10-Q. These forward-looking statements are not guarantees of future results and are subject to a number of risks and uncertainties, many of which are difficult to predict and beyond our control. Important factors that may cause actual results to differ materially from those in the forward-looking statements include, but are not limited to, a material delay in the Company's financial reporting, including the possibility that the Company will not be able to file its Form 10-Q within the five-day extension permitted by the rules of the U.S. Securities and Exchange Commission, and the possibility that the ongoing review may identify errors or control deficiencies in the Company's accounting practices. We disclaim and do not undertake any obligation to update or revise any forward-looking statement in this report, except as required by applicable law or regulation. 4