(1) Commentary is on a fully taxable-equivalent basis unless otherwise noted. Consistent with SEC guidance in Industry Guide 3 that contemplates the calculation of tax-exempt income on a tax equivalent basis, net interest income and net interest margin are provided on a fully taxable-equivalent basis, which generally assumes a 21% marginal tax rate. We provide detailed reconciliations in the Non-GAAP Performance and Financial Measures Reconciliation table on page 13. Exhibit 99.1 PRESS RELEASE ATLANTIC CAPITAL BANCSHARES, INC. REPORTS THIRD QUARTER 2021 RESULTS Atlanta, GA – October 27, 2021 – Atlantic Capital Bancshares, Inc. (NASDAQ: ACBI) announced net income for the quarter ended September 30, 2021, of $13.3 million, or $0.65 per diluted share, compared to $8.6 million, or $0.40 per diluted share, for the third quarter of 2020 and $11.8 million, or $0.58 per diluted share, for the second quarter of 2021. “With strong growth in loans, deposits, and revenue, Atlantic Capital recorded another quarter of solid operating results. Our clients are performing well, and Atlantic Capital is fueling their prosperity with reliable service and innovative solutions. New business pipelines are robust, and we expect continued strong momentum in the fourth quarter of this year and into 2022,” remarked Douglas Williams, President and Chief Executive Officer. Third Quarter Highlights(1)  Total assets were $4.2 billion, compared to $3.8 billion at June 30, 2021 and $2.9 billion at September 30, 2020.  Return on average assets totaled 1.36% and return on average equity was 14.69% in the third quarter of 2021.  Loans held for investment, excluding Paycheck Protection Program (“PPP”) loans, increased $66.3 million, or 12.3% annualized, from June 30, 2021, and increased $269.4 million, or 13.8%, from September 30, 2020.  Quarterly average deposits increased $106.3 million, or 12.9% annualized, compared to the second quarter of 2021 and increased $941.7 million, or 38.1%, compared to the third quarter of 2020.  Cost of deposits decreased to 0.08% from 0.10% in the second quarter of 2021 and from 0.19% in the third quarter of 2020.  Tangible book value per share increased to $16.94 from $16.40 at June 30, 2021 and from $15.11 at September 30, 2020.  Annualized net charge-offs to average loans totaled 0.00% for the third quarter of 2021 and 0.05% for the full year 2021. Non-performing assets to total assets were 0.10% at September 30, 2021.  The allowance for credit losses was 1.16% of total loans held for investment at September 30, 2021, compared to 1.27% at June 30, 2021 and 1.59% at September 30, 2020. Income Statement Taxable equivalent net interest income totaled $25.1 million for the third quarter of 2021, compared to $22.1 million in the third quarter of 2020 and $26.0 million in the second quarter of 2021. The third quarter of 2021 included $1.9 million in PPP loan income, compared to $3.0 million in the second quarter of 2021. The second quarter of 2021 also included $671,000 in interest income related to the receipt of an investment prepayment penalty and the accelerated accretion of a loan discount upon payoff. Taxable equivalent net interest margin was 2.69% in the third quarter of 2021, compared to 3.14% in the third quarter of 2020 and 2.91% in the second quarter of 2021. The taxable equivalent net interest margin excluding

PPP loans was 2.54% for the third quarter of 2021, compared to 2.70% for the second quarter of 2021. The yield on loans in the third quarter of 2021 was 3.91%, an increase of 9 basis points from the third quarter of 2020 and a decrease of 28 basis points from the second quarter of 2021. Excluding PPP loans, the third quarter of 2021 loan yield was 3.71%, a decrease of 24 basis points compared to the second quarter of 2021. In addition, loan interest income for the second quarter of 2021 included $405,000 in previously mentioned accelerated discount accretion. The cost of deposits in the third quarter of 2021 was 0.08%, a decrease of 11 basis points from the third quarter of 2020 and a decrease of 2 basis points from the second quarter of 2021. The cost of interest-bearing deposits decreased 13 basis points to 0.15% from the third quarter of 2020 and decreased 2 basis points from the second quarter of 2021. In the third quarter of 2021, we recorded a negative provision for credit losses of $2.4 million, compared to a provision for credit losses of $28,000 in the third quarter of 2020 and a negative provision for credit losses of $933,000 in the second quarter of 2021. Noninterest income totaled $4.6 million in the third quarter of 2021, compared to $2.5 million in the third quarter of 2020 and $3.6 million in the second quarter of 2021. Other noninterest income in the third quarter of 2021 totaled $1.1 million and included $930,000 in income from Small Business Investment Company (“SBIC”) funds. Noninterest expense totaled $15.0 million in the third quarter of 2021, compared to $13.7 million in the third quarter of 2020 and $15.2 million in the second quarter of 2021. The third quarter of 2021 included an expense reduction of $3.0 million as a result of the employee retention payroll tax credit pursuant to the CARES Act. Additionally, there were $2.9 million in merger related expenses. Balance Sheet Total loans held for investment were $2.3 billion at September 30, 2021, an increase of $85.8 million from September 30, 2020 and an increase of $9.0 million from June 30, 2021. Loans held for investment, excluding PPP loans, increased $66.3 million, or 12.3% annualized, from June 30, 2021, and increased $269.4 million, or 13.8%, from September 30, 2020. The allowance for credit losses was 1.16% of total loans held for investment at September 30, 2021, compared to 1.27% at June 30, 2021. The decrease in the allowance was a result of an improvement in our current expected credit losses, or CECL, economic forecast along with credit rating upgrades for certain criticized and classified loans. Excluding the impact of PPP loans, the allowance for credit losses at September 30, 2021 was 1.18%, compared to 1.33% at June 30, 2021. Total average deposits were $3.4 billion for the third quarter of 2021, an increase of $941.7 million, or 38.1%, from the third quarter of 2020 and an increase of $106.3 million, or 12.9% annualized, from the second quarter of 2021. Average noninterest bearing deposits were $1.4 billion for the third quarter of 2021, an increase of $520.4 million, or 61%, from the third quarter of 2020 and an increase of $79.4 million, or 24.5% annualized, from the second quarter of 2021. Noninterest bearing deposits were 40.3% of total average deposits in the third quarter of 2021, compared to 34.6% in the third quarter of 2020 and 39.2% in the second quarter of 2021. Merger Update On July 22, 2021, Atlantic Capital and SouthState Corporation (“SouthState”) entered into an Agreement and Plan of Merger, pursuant to which Atlantic Capital will merge with and into SouthState, with SouthState as the surviving corporation in the merger. The merger remains subject to approval by our shareholders at the Special Meeting scheduled for November 16, 2021, as well as approval by the Board of Governors of the Federal Reserve System. Approval of the merger from the Office of the Comptroller of the Currency has been received. 2

Non-GAAP Financial Measures Statements included in this press release include non-GAAP financial measures and should be read along with the accompanying tables, which provide a reconciliation of non-GAAP financial measures to GAAP financial measures. Atlantic Capital management uses non-GAAP financial measures, including: (i) taxable equivalent interest income; (ii) taxable equivalent net interest income; (iii) loans held for investment excluding PPP loans (iv) loan yield excluding PPP loans; (v) taxable equivalent net interest margin; (vi) taxable equivalent net interest margin excluding PPP loans; (vii) taxable equivalent income before income taxes; (viii) taxable equivalent income tax expense; (ix) tangible common equity to tangible assets; (x) tangible book value per share, and (xi) allowance for credit losses to loans held for investment excluding PPP loans, in our analysis of the Company's performance. Tangible common equity excludes goodwill from shareholders' equity. Management believes that non-GAAP financial measures provide a greater understanding of ongoing performance and operations and enhance comparability with prior periods. Non-GAAP financial measures should not be considered as an alternative to any measure of performance or financial condition as determined in accordance with GAAP, and investors should consider Atlantic Capital’s performance and financial condition as reported under GAAP and all other relevant information when assessing the performance or financial condition of the Company. Non-GAAP financial measures have limitations as analytical tools, and investors should not consider them in isolation or as a substitute for analysis of the results or financial condition as reported under GAAP. Non-GAAP financial measures may not be comparable to non- GAAP financial measures presented by other companies. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended and Section 21E of the Securities Exchange Act of 1934, as amended. These forward- looking statements represent plans, estimates, objectives, goals, guidelines, expectations, intentions, projections and statements of our beliefs concerning future events, business plans, objectives, expected operating results and the assumptions upon which those statements are based. Forward-looking statements include without limitation, any statement that may predict, forecast, indicate or imply future results, performance or achievements, and are typically identified with words such as “may,” “could,” “should,” “will,” “would,” “believe,” “anticipate,” “estimate,” “project,” “expect,” “intend,” “plan,” “strive,” or words or phases of similar meaning. Forward-looking statements may include, among other things, statements about the proposed merger with SouthState, Atlantic Capital’s confidence in its strategies and its expectations about financial performance, the impact of COVID-19 on operations, market growth, market and regulatory trends and developments, acquisitions and divestitures, new technologies, services and opportunities and earnings. The forward-looking statements are based largely on Atlantic Capital’s expectations and are subject to a number of known and unknown risks and uncertainties that are subject to change based on factors which are, in many instances, beyond Atlantic Capital’s control. Atlantic Capital undertakes no obligation to publicly update any forward-looking statement to reflect developments occurring after the statement is made, except as otherwise required by law. Actual results, performance or achievements could differ materially from those contemplated, expressed, or implied by the forward-looking statements as a result of, among other factors, the risks and uncertainties described in “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in Atlantic Capital’s Annual Report on Form 10-K. Additional information and other factors that could affect future financial results are included in Atlantic Capital’s subsequent filings with the SEC. Please refer to the SEC’s website at www.sec.gov where you can review those documents. Important Additional Information SouthState filed a registration statement on Form S-4 with the SEC on September 15, 2021, to register the shares of SouthState common stock that will be issued to Atlantic Capital’s shareholders in connection with the merger. The registration statement, which became effective on October 15, 2021, includes a proxy statement/prospectus and other relevant materials in connection with the transaction. BEFORE MAKING ANY VOTING OR INVESTMENT DECISION, INVESTORS AND SECURITY HOLDERS ARE URGED TO 3

READ THE PROXY STATEMENT/PROSPECTUS REGARDING THE MERGER AND ANY OTHER RELEVANT DOCUMENTS CAREFULLY IN THEIR ENTIRETY BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT THE MERGER. Investors and security holders may obtain free copies of these documents and other documents filed with the SEC on its website at http://www.sec.gov. Investors and security holders may also obtain free copies of the documents filed with the SEC by Atlantic Capital on our website at www.atlanticcapitalbank.com and by SouthState on its website at www.southstatebank.com. This press release does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. Before making any voting or investment decision, investors and security holders of Atlantic Capital and SouthState are urged to read carefully the entire registration statement and proxy statement/prospectus, including any amendments thereto, because they contain important information about the merger. Free copies of these documents may be obtained as described above. Participants in the Merger Atlantic Capital and SouthState, and certain of their respective directors, executive officers and other members of management and employees, may be deemed to be participants in the solicitation of proxies from Atlantic Capital’s shareholders in respect of the merger. Information regarding such persons who may be deemed participants in the solicitation of proxies from Atlantic Capital’s shareholders is included in the proxy statement/prospectus for Atlantic Capital’s meeting of shareholders, which was filed by SouthState on Form S- 4 on September 15, 2021 and declared effective on October 15, 2021. Information about Atlantic Capital’s directors and executive officers and their ownership of Atlantic Capital common stock can also be found in definitive proxy statement filed in connection with its 2021 annual meeting of shareholders on May 20, 2021, and other documents subsequently filed by Atlantic Capital with the SEC. Information about SouthState’s directors and executive officers and their ownership of SouthState common stock can also be found in SouthState’s definitive proxy statement filed in connection with its 2021 annual meeting of shareholders on April 28, 2021, and other documents subsequently filed by SouthState with the SEC. Information regarding the interests of such participants is included in the proxy statement/prospectus and other relevant documents regarding the merger filed with the SEC. About Atlantic Capital Bancshares Atlantic Capital Bancshares, Inc. is a $4.2 billion publicly traded bank holding company headquartered in Atlanta, Georgia. Atlantic Capital offers commercial and not-for-profit banking services, specialty corporate financial services, private banking services and commercial real estate finance solutions to privately held companies and individuals in the Atlanta area, as well as payments and other specialized financial services for select clients nationally. Media Contact: Ashley Carson Email: ashley.carson@atlcapbank.com Phone: 404-995-6050 (ACB-ER) Financial Contact: Patrick Oakes Email: patrick.oakes@atlcapbank.com Phone: 404-995-6050 4

ATLANTIC CAPITAL BANCSHARES, INC. Selected Financial Information (in thousands, except share and per share data; taxable equivalent) INCOME SUMMARY Interest income - taxable equivalent (1) $ 27,040 $ 27,993 $ 25,775 $ 25,288 $ 24,578 $ 80,808 $ 74,976 Interest expense 1,895 1,958 2,065 2,299 2,515 5,918 9,724 Net interest income - taxable equivalent 25,145 26,035 23,710 22,989 22,063 74,890 65,252 Provision for credit losses (2,405) (933) (4,519) 481 28 (7,857) 16,965 Net interest income after provision for credit losses 27,550 26,968 28,229 22,508 22,035 82,747 48,287 Noninterest income 4,609 3,584 3,562 3,016 2,504 11,755 7,269 Noninterest expense 15,018 15,197 15,149 13,164 13,713 45,364 39,494 Income before income taxes 17,141 15,355 16,642 12,360 10,826 49,138 16,062 Income tax expense 3,837 3,539 3,280 2,410 2,208 10,656 3,471 Net income(1)(2) $ 13,304 $ 11,816 $ 13,362 $ 9,950 $ 8,618 $ 38,482 $ 12,591 PER SHARE DATA Diluted earnings per share $ 0.65 $ 0.58 $ 0.65 $ 0.48 $ 0.40 $ 1.88 $ 0.58 Book value per share 17.92 17.38 16.72 16.60 16.05 17.92 16.05 Tangible book value per common share (3) 16.94 16.40 15.74 15.62 15.11 16.94 15.11 PERFORMANCE MEASURES Return on average equity 14.69 % 13.60 % 15.99 % 11.68 % 10.05 % 14.74 % 4.98 % Return on average assets 1.36 1.26 1.50 1.19 1.15 1.37 0.59 Taxable equivalent net interest margin 2.69 2.91 2.81 2.91 3.14 2.80 3.25 Taxable equivalent net interest margin excluding PPP loans 2.54 2.70 2.70 2.81 3.18 2.65 3.31 Efficiency ratio 51.12 51.97 56.30 51.30 56.61 53.04 55.16 Average loans to average deposits 65.81 67.54 71.93 76.81 88.65 68.32 87.07 CAPITAL Average equity to average assets 9.23 % 9.24 % 9.39 % 10.18 % 11.45 % 9.28 % 11.78 % Tangible common equity to tangible assets 8.21 8.86 8.63 8.86 11.03 8.21 11.03 Leverage ratio 8.50 (3) 8.4 8.4 8.9 9.9 8.73 (3) 9.9 Total risk based capital ratio 15.91 (3) 16.0 16.4 16.1 16.9 15.91 (3) 16.9 SHARES OUTSTANDING Number of common shares outstanding - basic 20,305,109 20,319,429 20,354,077 20,394,912 21,202,783 20,305,109 21,202,783 Number of common shares outstanding - diluted 20,590,747 20,595,812 20,617,188 20,492,542 21,298,098 20,590,747 21,298,098 Average number of common shares - basic 20,308,761 20,332,503 20,380,066 20,711,089 21,500,735 20,340,182 21,553,953 Average number of common shares - diluted 20,507,604 20,516,478 20,502,184 20,795,332 21,543,805 20,508,775 21,640,057 ASSET QUALITY Allowance for credit losses to loans held for investment 1.16 % 1.27 % 1.31 % 1.55 % 1.59 % 1.16 % 1.59 % Net charge-offs to average loans (4) 0.00 0.10 0.04 0.05 0.06 0.05 0.13 Non-performing assets to total assets 0.10 0.14 0.06 0.13 0.20 0.10 0.20 AVERAGE BALANCES Total loans $ 2,246,529 $ 2,233,906 $ 2,270,660 $ 2,207,956 $ 2,191,669 $ 2,250,277 $ 2,071,673 Investment securities 733,452 656,507 579,547 491,134 453,382 657,066 444,766 Total assets 3,893,049 3,771,970 3,611,417 3,328,719 2,977,444 3,759,841 2,865,884 Deposits 3,413,882 3,307,601 3,156,906 2,874,402 2,472,218 3,293,738 2,379,235 Shareholders' equity 359,300 348,416 338,990 338,948 341,017 348,974 337,521 AT PERIOD END Loans and loans held for sale $ 2,285,670 $ 2,264,899 $ 2,302,661 $ 2,249,036 $ 2,188,894 $ 2,285,670 $ 2,188,894 Investment securities 772,987 714,065 613,236 535,579 446,706 772,987 446,706 Total assets 4,210,316 3,780,445 3,732,668 3,615,617 2,923,977 4,210,316 2,923,977 Deposits 3,727,321 3,306,224 3,277,692 3,161,508 2,468,722 3,727,321 2,468,722 Shareholders’ equity 363,925 353,185 340,328 338,586 340,309 363,925 340,309 (1)Interest income on tax-exempt securities has been increased to reflect comparable interest on taxable securities. The rate used was 21%, reflecting the statutory federal income tax rate. (2)Excludes effect of acquisition related intangibles. (3)Amounts are estimates as of September 30, 2021. (4)Annualized. Fourth Quarter Quarter 2020 2021 Quarter First Quarter Third Second For the nine months ended 2021 2020 Quarter September 30, Third 5

ATLANTIC CAPITAL BANCSHARES, INC. Consolidated Balance Sheets (unaudited) (in thousands, except share data) ASSETS Cash and due from banks $ 25,725 $ 35,530 $ 16,865 $ 22,715 Interest-bearing deposits in banks 811,168 593,195 636,537 91,243 Other short-term investments 140,848 — — — Cash and cash equivalents 977,741 628,725 653,402 113,958 Investment securities available for sale 535,158 480,518 335,423 260,884 Investment securities held to maturity, net of allowance for credit losses of $13, $13, $14, and $15 at September 30,2021, June 30, 2021, December 31, 2020 and September 30, 2020, respectively 237,829 233,547 200,156 185,822 Other investments 23,877 24,293 25,892 26,315 Loans held for sale 11,814 — — 859 Loans held for investment 2,273,856 2,264,899 2,249,036 2,188,035 Less: allowance for loan losses (23,924) (26,123) (31,818) (31,894) Loans held for investment, net 2,249,932 2,238,776 2,217,218 2,156,141 Premises and equipment, net 18,517 19,643 21,589 22,558 Bank owned life insurance 74,000 73,610 72,856 67,489 Goodwill 19,925 19,925 19,925 19,925 Other intangibles, net 2,573 2,637 2,731 2,685 Other real estate owned — 16 16 563 Other assets 58,950 58,755 66,409 66,778 Total assets $ 4,210,316 $ 3,780,445 $ 3,615,617 $ 2,923,977 LIABILITIES AND SHAREHOLDERS’ EQUITY Deposits: Noninterest-bearing demand $ 1,691,616 $ 1,374,018 $ 1,033,765 $ 843,656 Interest-bearing checking 721,525 536,677 760,638 387,858 Savings 800 676 625 568 Money market 930,929 1,026,239 1,030,753 945,834 Time 287,865 283,656 241,328 196,343 Brokered deposits 94,586 84,958 94,399 94,463 Total deposits 3,727,321 3,306,224 3,161,508 2,468,722 Long-term debt 74,024 73,953 73,807 73,814 Other liabilities 45,046 47,083 41,716 41,132 Total liabilities 3,846,391 3,427,260 3,277,031 2,583,668 SHAREHOLDERS’ EQUITY Preferred stock, no par value; 10,000,000 shares authorized; no shares issued and outstanding as of September 30, 2021, June 30, 2021, December 31, 2020 and September 30, 2020 — — — — Common stock, no par value; 100,000,000 shares authorized; 20,305,109, 20,319,429, 20,394,912, and 21,202,783 shares issued and outstanding as of September 30, 2021, June 30, 2021, December 31, 2020 and September 30, 2020, respectively 207,214 206,619 209,942 220,643 Retained earnings 152,619 139,315 114,137 104,188 Accumulated other comprehensive income 4,092 7,251 14,507 15,478 Total shareholders’ equity 363,925 353,185 338,586 340,309 TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY $ 4,210,316 $ 3,780,445 $ 3,615,617 $ 2,923,977 September 30, 2021 September 30, 2020 December 31, 2020 June 30, 2021 6

face="Arial" style="color:white;font-size:1.0pt;">ATLANTIC CAPITAL BANCSHARES, INC. of Income (unaudited) share and per share data) 22,151 $ 23,352 $ 21,769 $ 21,609 $ 21,049 $ 67,272 $ 63,971 3,920 3,900 3,374 3,000 2,910 11,194 8,683 on other interest‑earning assets 593 366 267 334 274 1,226 1,399 26,664 27,618 25,410 24,943 24,233 79,692 74,053 789 851 971 1,188 1,151 2,611 6,632 Home Loan Bank advances — — — — 16 — 54 funds purchased and securities sold — — — 3 — 41 1,106 1,107 1,094 1,111 1,345 3,307 2,997 1,895 1,958 2,065 2,299 2,515 5,918 9,724 25,660 23,345 22,644 21,718 73,774 64,329 (933) (4,519) 481 28 (7,857) 16,965 26,593 27,864 22,163 21,690 81,631 47,364 1,727 1,663 1,341 1,217 5,155 3,530 — — 2 (23) — 2 — 38 — — (6) (145) 38 (140) 21 (7) 47 11 10 61 246 391 388 391 368 363 1,170 1,092 1,276 1,231 1,225 1,015 893 3,732 2,089 1,118 245 234 310 166 1,597 452 4,609 3,584 3,562 3,016 2,504 11,755 7,269 10,290 10,362 10,421 8,437 8,850 31,073 25,792 — — — — (3,035) — 778 734 767 739 2,268 2,416 857 819 774 969 826 2,450 2,368 737 723 922 686 562 2,382 2,059 889 869 792 789 757 2,550 2,324 142 138 108 144 141 388 373 91 47 10 14 39 148 213 421 275 241 213 1,174 388 2,899 — — — — 2,899 — 914 1,040 1,113 1,117 1,586 3,067 3,561 15,018 15,197 15,149 13,164 13,713 45,364 39,494 14,980 16,277 12,015 10,481 48,022 15,139 3,461 3,164 2,915 2,065 1,863 9,540 2,548 11,816 $ 13,362 $ 9,950 $ 8,618 $ 38,482 $ 12,591 0.66 $ 0.58 $ 0.66 $ 0.48 $ 0.40 $ 1.89 $ 0.58 0.65 $ 0.58 $ 0.65 $ 0.48 $ 0.40 $ 1.88 $ 0.58 20,308,761 20,332,503 20,380,066 20,711,089 21,500,735 20,340,182 21,553,953 20,507,604 20,516,478 20,502,184 20,795,332 21,543,805 20,508,775 21,640,057

Tax Tax Equivalent Equivalent ATLANTIC CAPITAL BANCSHARES, INC. Average Balance Sheets and Net Interest Margin Analysis Selected Financial Information (dollars in thousands; taxable equivalent) Yield/Rate Yield/Rate Assets Interest bearing deposits in other banks $ 594,338 $ 266 0.18 % $ 687,795 $ 201 0.12 % Other short-term investments 122,477 156 0.51 — — — Investment securities: Taxable investment securities 503,420 2,411 1.90 426,634 2,382 2.24 Non-taxable investment securities (1) 230,032 1,885 3.25 229,873 1,893 3.30 Total investment securities 733,452 4,296 2.32 656,507 4,275 2.61 Loans 2,246,529 22,151 3.91 2,233,906 23,352 4.19 FHLB and FRB stock 11,931 171 5.69 11,931 165 5.55 Total interest-earning assets 3,708,727 27,040 2.89 3,590,139 27,993 3.13 Non-earning assets 184,322 181,831 Total assets $ 3,893,049 $ 3,771,970 Liabilities Interest bearing deposits: NOW, money market, and savings 1,665,462 680 0.16 1,637,374 725 0.18 Time deposits 285,808 50 0.07 290,331 68 0.09 Brokered deposits 87,498 59 0.27 84,168 58 0.28 Total interest-bearing deposits 2,038,768 789 0.15 2,011,873 851 0.17 Total borrowings — — — 89 — — Total long-term debt 73,978 1,106 5.93 73,904 1,107 6.01 Total interest-bearing liabilities 2,112,746 1,895 0.36 2,085,866 1,958 0.38 Demand deposits 1,375,114 1,295,728 Other liabilities 45,889 41,960 Shareholders’ equity 359,300 348,416 Total liabilities and shareholders’ equity $ 3,893,049 $ 3,771,970 Net interest spread 2.53 % 2.75 % Net interest income and net interest margin (2) $25,145 2.69 % $ 26,035 2.91 % Non-taxable equivalent net interest margin 2.65 % 2.87 % Tax Tax Equivalent Equivalent ATLANTIC CAPITAL BANCSHARES, INC. Average Balance Sheets and Net Interest Margin Analysis Selected Financial Information (dollars in thousands; taxable equivalent) Yield/Rate Yield/Rate Assets Interest bearing deposits in other banks $ 594,338 $ 266 0.18 % $ 136,459 $ 65 0.19 % Other short-term investments 122,477 156 0.51 — — — Investment securities: Taxable investment securities 503,420 2,411 1.90 237,655 1,467 2.46 Non-taxable investment securities (1) 230,032 1,885 3.25 215,727 1,788 3.30 Total investment securities 733,452 4,296 2.32 453,382 3,255 2.86 Loans 2,246,529 22,151 3.91 2,191,669 21,049 3.82 FHLB and FRB stock 11,931 171 5.69 14,484 209 5.74 Total interest-earning assets 3,708,727 27,040 2.89 2,795,994 24,578 3.50 Non-earning assets 184,322 181,450 Total assets $ 3,893,049 $ 2,977,444 Liabilities Interest bearing deposits: NOW, money market, and savings 1,665,462 680 0.16 1,383,382 1,006 0.29 Time deposits 285,808 50 0.07 166,019 86 0.21 Brokered deposits 87,498 59 0.27 68,102 59 0.34 Total interest-bearing deposits 2,038,768 789 0.15 1,617,503 1,151 0.28 Total borrowings — — — 40,793 19 0.19 Total long-term debt 73,978 1,106 5.93 82,708 1,345 6.47 Total interest-bearing liabilities 2,112,746 1,895 0.36 1,741,004 2,515 0.57 Demand deposits 1,375,114 854,715 Other liabilities 45,889 40,708 Shareholders’ equity 359,300 341,017 Total liabilities and shareholders’ equity $ 3,893,049 $ 2,977,444 Net interest spread 2.53 % 2.92 % Net interest income and net interest margin (2) $25,145 2.69 % $ 22,063 3.14 % Non-taxable equivalent net interest margin 2.65 % 3.09 % Interest Income/ Expense Three months ended September 30, 2021 September 30, 2020 Interest Income/ Expense Average Balance Average Balance Three months ended June 30, 2021 Interest Income/ Expense Interest Income/ Expense September 30, 2021 Average Balance Average Balance (1) Interest revenue on tax-exempt securities has been increased to reflect comparable interest on taxable securities. The rate used was 21%, reflecting the statutory federal income tax rate. (2) Tax equivalent net interest income divided by total interest-earning assets using the appropriate day count convention based on the type of interest-earning asset. (1) Interest revenue on tax-exempt securities has been increased to reflect comparable interest on taxable securities. The rate used was 21%, reflecting the statutory federal income tax rate. (2) Tax equivalent net interest income divided by total interest-earning assets using the appropriate day count convention based on the type of interest-earning asset. 8

ATLANTIC CAPITAL BANCSHARES, INC. Average Balance Sheets and Net Interest Margin Analysis Selected Financial Information Tax Tax Equivalent Equivalent (dollars in thousands; taxable equivalent) Yield/Rate Yield/Rate Assets Interest bearing deposits in other banks $ 615,001 $ 634 0.14 % $ 147,795 $ 756 0.68 % Other short-term investments 41,274 156 0.51 36 — — Investment securities: Taxable investment securities 429,307 6,691 2.08 246,388 4,729 2.56 Non-taxable investment securities (1) 227,759 5,619 3.30 198,378 4,877 3.28 Total investment securities 657,066 12,310 2.50 444,766 9,606 2.88 Loans 2,250,277 67,272 4.00 2,071,673 63,971 4.12 FHLB and FRB stock 12,183 436 4.78 14,667 643 5.86 Total interest-earning assets 3,575,801 80,808 3.02 2,678,937 74,976 3.74 Non-earning assets 184,040 186,947 Total assets $ 3,759,841 $ 2,865,884 Liabilities Interest bearing deposits: NOW, money market, and savings 1,654,990 2,240 0.18 1,397,280 5,889 0.56 Time deposits 283,296 191 0.09 106,271 196 0.25 Brokered deposits 85,454 180 0.28 81,125 547 0.90 Total interest-bearing deposits 2,023,740 2,611 0.17 1,584,676 6,632 0.56 Total borrowings 30 — — 50,055 95 0.25 Total long-term debt 73,905 3,307 5.98 60,922 2,997 6.57 Total interest-bearing liabilities 2,097,675 5,918 0.38 1,695,653 9,724 0.77 Demand deposits 1,269,998 794,559 Other liabilities 43,194 38,151 Shareholders’ equity 348,974 337,521 Total liabilities and shareholders’ equity $ 3,759,841 $ 2,865,884 Net interest spread 2.64 % 2.97 % Net interest income and net interest margin (2) $74,890 2.80 % $ 65,252 3.25 % Non-taxable equivalent net interest margin 2.76 % 3.21 % (1) Interest revenue on tax-exempt securities has been increased to reflect comparable interest on taxable securities. The rate used was 21%, reflecting the statutory federal income tax rate. Nine months ended September 30, 2020 Interest Income/ Expense September 30, 2021 Average Balance Average Balance Income/ (2) Tax equivalent net interest income divided by total interest-earning assets using the appropriate day count convention based on the type of interest-earning asset. Expense Interest 9

ATLANTIC CAPITAL BANCSHARES, INC. Period End Loans (dollars in thousands) Loans held for sale Loans held for sale $ 11,814 $ — $ 1,847 $ — $ 859 $ 11,814 $ 10,955 Total loans held for sale $ 11,814 $ — $ 1,847 $ — $ 859 $ 11,814 $ 10,955 Loans held for investment Commercial loans: Commercial and industrial - other $ 790,437 $ 767,646 $ 735,287 $ 760,645 $ 712,567 $ 22,791 $ 77,870 Commercial and industrial - PPP 48,304 105,684 218,766 192,160 231,834 (57,380) (183,530) Commercial real estate: Multifamily 62,906 58,632 80,507 66,262 58,336 4,274 4,570 Owner occupied 413,875 392,108 381,018 373,689 364,170 21,767 49,705 Investment 483,538 506,230 480,566 469,150 458,279 (22,692) 25,259 Construction and land: 1‑4 family residential construction 2,338 2,074 1,578 1,171 — 264 2,338 Other construction, development, and land 202,810 178,423 141,218 144,424 139,836 24,387 62,974 Total commercial loans 2,004,208 2,010,797 2,038,940 2,007,501 1,965,022 (6,589) 39,186 Residential: Residential mortgages 47,076 45,207 31,817 33,783 29,460 1,869 17,616 Home equity 28,943 24,972 26,293 25,443 24,528 3,971 4,415 Total residential loans 76,019 70,179 58,110 59,226 53,988 5,840 22,031 Consumer 192,462 184,203 203,176 176,066 154,916 8,259 37,546 Other 4,921 5,234 7,689 13,897 22,777 (313) (17,856) 2,277,610 2,270,413 2,307,915 2,256,690 2,196,703 7,197 80,907 Less net deferred fees and other unearned income (3,754) (5,514) (7,101) (7,654) (8,668) 1,760 4,914 Total loans held for investment $ 2,273,856 $ 2,264,899 $ 2,300,814 $ 2,249,036 $ 2,188,035 $ 8,957 $ 85,821 Total loans $ 2,285,670 $ 2,264,899 $ 2,302,661 $ 2,249,036 $ 2,188,894 $ 20,771 $ 96,776 Total unfunded commitments $ 848,642 $ 804,784 $ 789,869 $ 813,757 $ 764,247 $ 43,858 $ 84,395 September 30, 2021 March 31, 2021 December 31, 2020 June 30, 2021 Year Over Year Change 2020 Linked Quarter Change September 30, 10

ATLANTIC CAPITAL BANCSHARES, INC. Allowance for Credit Losses Activity and Credit Quality (dollars in thousands) Allowance for loan losses Balance at beginning of period $ 26,123 $ 27,506 $ 31,818 $ 31,894 $ 31,605 Provision for loan losses (2,221) (814) (4,074) 225 636 Loans charged-off: Commercial and industrial (131) (386) (288) (401) (404) Commercial real estate — — — — — Construction and land — — — — — Residential mortgages — (223) — — — Home equity — — — — — Consumer — — — — — Other — — — — — Total loans charged-off (131) (609) (288) (401) (404) Recoveries on loans previously charged-off: Commercial and industrial 151 6 50 37 56 Commercial real estate — — — 44 — Construction and land — — — 18 — Residential mortgages — 32 — — — Home equity — — — — — Consumer 2 2 — 1 1 Other — — — — — Total recoveries 153 40 50 100 57 Net charge-offs $22 $ (569) $ (238) $ (301) $ (347) Balance at period end $ 23,924 $ 26,123 $ 27,506 $ 31,818 $ 31,894 Allowance for unfunded commitments Balance at beginning of period $ 2,565 $ 2,683 $ 3,128 $ 2,871 $ 3,480 Provision for unfunded commitments (185) (118) (445) 257 (609) Balance at period end $ 2,380 $ 2,565 $ 2,683 $ 3,128 $ 2,871 Total allowance for credit losses - loans and unfunded commitments $ 26,304 $ 28,688 $ 30,189 $ 34,946 $ 34,765 Provision for credit losses under CECL Provision for loan losses (2,221) (814) (4,074) 225 636 Provision for securities held to maturity credit losses 1 (1) - (1) 1 Provision for unfunded commitments (185) (118) (445) 257 (609) Total provision for credit losses $ (2,405) $ (933) $ (4,519) $ 481 $ 28 Non-performing loans $ 4,077 $ 5,194 $ 2,056 $ 4,862 $ 5,421 Foreclosed properties (OREO) — 16 16 16 563 Total nonperforming assets $ 4,077 $ 5,210 $ 2,072 $ 4,878 $ 5,984 Allowance for loan losses to loans held for investment 1.05 % 1.15 % 1.20 % 1.41 % 1.46 % Allowance for credit losses to loans held for investment 1.16 % 1.27 % 1.31 % 1.55 % 1.59 % Allowance for credit losses to loans held for investment excluding PPP loans 1.18 % 1.33 % 1.45 % 1.70 % 1.78 % Net charge-offs to average loans (1) 0.00 0.10 0.04 0.05 0.06 Non-performing loans as a percentage of total loans 0.18 % 0.23 % 0.09 % 0.22 % 0.25 % Non-performing assets as a percentage of total assets 0.10 % 0.14 % 0.06 % 0.13 % 0.20 % (1)Annualized. Third Quarter Second Quarter 2021 First Quarter Fourth Quarter 2020 Quarter Third 11

ATLANTIC CAPITAL BANCSHARES, INC. Period End Deposits (dollars in thousands) DDA $ 1,691,616 $ 1,374,018 $ 1,280,524 $ 1,033,765 $ 843,656 $ 317,598 $ 847,960 NOW 721,525 536,677 485,540 760,638 387,858 184,848 333,667 Savings 800 676 562 625 568 124 232 Money market 930,929 1,026,239 1,142,361 1,030,753 945,834 (95,310) (14,905) Time 287,865 283,656 294,129 241,328 196,343 4,209 91,522 Brokered 94,586 84,958 74,576 94,399 94,463 9,628 123 Total deposits $ 3,727,321 $ 3,306,224 $ 3,277,692 $ 3,161,508 $ 2,468,722 $ 421,097 $ 1,258,599 Average Deposits (dollars in thousands) DDA $ 1,375,114 $ 1,295,728 $ 1,136,531 $ 977,009 $ 854,715 $ 79,386 $ 520,399 NOW 607,485 548,358 618,701 558,967 440,734 59,127 $ 166,751 Savings 731 593 587 614 586 138 $ 145 Money market 1,057,246 1,088,423 1,042,809 1,026,347 942,062 (31,177) $ 115,184 Time 285,808 290,331 273,615 221,792 166,019 (4,523) $ 119,789 Brokered 87,498 84,168 84,663 89,673 68,102 3,330 $ 19,396 Total deposits $ 3,413,882 $ 3,307,601 $ 3,156,906 $ 2,874,402 $ 2,472,218 $ 106,281 $ 941,664 Noninterest bearing deposits as a percentage of average deposits 40.3 % 39.2 % 36.0 % 34.0 % 34.6 % Cost of interest-bearing deposits 0.15 % 0.17 % 0.19 % 0.25 % 0.28 % Cost of deposits 0.08 % 0.10 % 0.12 % 0.16 % 0.19 % Linked Quarter Change September 30, 2021 Year Over Year Change 2021 June 30, December 31, 2020 2020 September 30, March 31, 2021 Linked 2020 2021 Quarter Q3 2021 vs Third Second First Fourth Third Change Q3 2020 Quarter Quarter Quarter Quarter Quarter 12

ATLANTIC CAPITAL BANCSHARES, INC. Non-GAAP Performance and Financial Measures Reconciliation (in thousands, except share and per share data) Taxable equivalent interest income reconciliation Interest income - GAAP $ 26,664 $ 27,618 $ 25,410 $ 24,943 $ 24,233 $ 79,692 $ 74,053 Taxable equivalent adjustment 376 375 365 345 345 1,116 923 Interest income - taxable equivalent $ 27,040 $ 27,993 $ 25,775 $ 25,288 $ 24,578 $ 80,808 $ 74,976 Taxable equivalent net interest income reconciliation Net interest income - GAAP $ 24,769 $ 25,660 $ 23,345 $ 22,644 $ 21,718 $ 73,774 $ 64,329 Taxable equivalent adjustment 376 375 365 345 345 1,116 923 Net interest income - taxable equivalent $ 25,145 $ 26,035 $ 23,710 $ 22,989 $ 22,063 $ 74,890 $ 65,252 Loan yield excluding PPP loans reconciliation Loan yield - GAAP 3.91 % 4.19 % 3.89 % 3.89 % 3.82 % 4.00 % 4.12 % Impact of PPP loans (0.20) (0.24) (0.06) (0.03) 0.13 (0.17) 0.14 Loan yield excluding PPP loans 3.71 % 3.95 % 3.83 % 3.86 % 3.95 % 3.83 % 4.26 % Taxable equivalent net interest margin reconciliation Net interest margin - GAAP 2.65 % 2.87 % 2.76 % 2.86 % 3.09 % 2.76 % 3.21 % Impact of taxable equivalent adjustment 0.04 0.04 0.05 0.05 0.05 0.04 0.04 Net interest margin - taxable equivalent 2.69 % 2.91 % 2.81 % 2.91 % 3.14 % 2.80 % 3.25 % Taxable equivalent net interest margin excluding PPP loans reconciliation Net interest margin - taxable equivalent 2.69 % 2.91 % 2.81 % 2.91 % 3.14 % 2.80 % 3.21 % Impact of PPP loans (0.15) (0.21) (0.11) (0.10) 0.04 (0.15) 0.10 Net interest margin - taxable equivalent excluding PPP loans 2.54 % 2.70 % 2.70 % 2.81 % 3.18 % 2.65 % 3.31 % Taxable equivalent income before income taxes reconciliation Income before income taxes - GAAP $ 16,765 $ 14,980 $ 16,277 $ 12,015 $ 10,481 $ 48,022 $ 15,139 Taxable equivalent adjustment 376 375 365 345 345 1,116 923 Income before income taxes $ 17,141 $ 15,355 $ 16,642 $ 12,360 $ 10,826 $ 49,138 $ 16,062 Taxable equivalent income tax expense reconciliation Income tax expense - GAAP $ 3,461 $ 3,164 $ 2,915 $ 2,065 $ 1,863 $ 9,540 $ 2,548 Taxable equivalent adjustment 376 375 365 345 345 1,116 923 Income tax expense $ 3,837 $ 3,539 $ 3,280 $ 2,410 $ 2,208 $ 10,656 $ 3,471 Tangible book value per common share reconciliation Total shareholders’ equity $ 363,925 $ 353,185 $ 340,328 $ 338,586 $ 340,309 $ 363,925 $ 340,309 Intangible assets (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) Total tangible common equity $ 344,000 $ 333,260 $ 320,403 $ 318,661 $ 320,384 $ 344,000 $ 320,384 Common shares outstanding 20,305,109 20,319,429 20,354,077 20,394,912 21,202,783 20,305,109 21,202,783 Book value per common share - GAAP $ 17.92 $ 17.38 $ 16.72 $ 16.60 $ 16.05 $ 17.92 $ 16.05 Tangible book value 16.94 16.40 15.74 15.62 15.11 16.94 15.11 Tangible common equity to tangible assets reconciliation Total shareholders’ equity $ 363,925 $ 353,185 $ 340,328 $ 338,586 $ 340,309 $ 363,925 $ 340,309 Intangible assets (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) Total tangible common equity $ 344,000 $ 333,260 $ 320,403 $ 318,661 $ 320,384 $ 344,000 $ 320,384 Total assets $ 4,210,316 $ 3,780,445 $ 3,732,668 $ 3,615,617 $ 2,923,977 $ 4,210,316 $ 2,923,977 Intangible assets (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) (19,925) Total tangible assets $ 4,190,391 $ 3,760,520 $ 3,712,743 $ 3,595,692 $ 2,904,052 $ 4,190,391 $ 2,904,052 Tangible common equity to tangible assets 8.21 % 8.86 % 8.63 % 8.86 % 11.03 % 8.21 % 11.03 % Allowance for credit losses to loans held for investment reconciliation Total loans held for investment $ 2,273,856 $ 2,264,899 $ 2,300,814 $ 2,249,036 $ 2,188,035 $ 2,273,856 $ 2,188,035 PPP loans (48,304) (105,684) (218,766) (192,160) (231,834) (48,304) (231,834) Total loans held for investment excluding PPP loans $ 2,225,552 $ 2,159,215 $ 2,082,048 $ 2,056,876 $ 1,956,201 $ 2,225,552 $ 1,956,201 Allowance for credit losses to loans held for investment 1.16 % 1.27 % 1.31 % 1.55 % 1.59 % 1.16 % 1.59 % Allowance for credit losses to loans held for investment excluding PPP loans 1.18 % 1.33 % 1.45 % 1.70 % 1.78 % 1.18 % 1.78 % Second Quarter 2021 For the nine months ended September 30, 2021 2020 Third Quarter First Quarter 2020 Third Quarter Fourth Quarter 13