Third Coast Bancshares, Inc.

Filed by Third Coast Bancshares, Inc. pursuant to Rule 425 under the Securities Act of 1933 and deemed filed pursuant to Rule 14a-12 under the Securities Exchange Act of 1934 Subject Company: Great Plains Bancshares, Inc. Commission File No.: 001-41028 Date: October 22, 2026

The following is a transcript of a conference call hosted by Third Coast Bancshares, Inc. on October 22, 2026, which discusses, among other things, the transaction with Great Plains Bancshares, Inc.: CORPORATE PARTICIPANTS

Natalie S. Hairston Executive Vice President, Dennard Lascar Investor Relations Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. R. John McWhorter Senior Executive Vice President & Chief Financial Officer, Third Coast Bancshares, Inc. Audrey A. Spaulding Senior Executive Vice President & Chief Credit Officer, Third Coast Bancshares, Inc. ..................................................................................................................................................................................................................................................................... OTHER PARTICIPANTS

Michael Rose Analyst, Raymond James Financial, Inc. Hannah Wynn Analyst, Keefe, Bruyette & Woods, Inc. Brett Rabatin Analyst, StoneX Group, Inc. (Investment Management) Bernard von-Gizycki Analyst, Deutsche Bank Securities, Inc. Matt Olney Analyst, Stephens, Inc. Dave Storms Analyst, Stonegate Capital Markets, Inc Jackson Andrew Analyst, Piper Sandler & Co. (Broker) .....................................................................................................................................................................................................................................................................

MANAGEMENT DISCUSSION SECTION Operator : Greetings and welcome to the Third Coast Bancshares Third Quarter Earnings Conference Call. At this time, all participants are in a listen only mode. A question-and-answer session will follow the formal presentation. [Operator Instructions] As a reminder, this conference is being recorded. It's now my pleasure to introduce Natalie Hairston of Investor Relations. Please go ahead. Natalie, please go ahead. ..................................................................................................................................................................................................................................................................... Natalie S. Hairston Executive Vice President, Dennard Lascar Investor Relations Good morning and thank you for joining us for Third Coast Bancshares Inc third quarter 2026 earnings conference call. With me today are Bart Caraway, Founder, Chairman, President and Chief Executive Officer; John McWhorter, Chief Financial Officer; and Audrey Spaulding, Chief Credit Officer. First, a few housekeeping items. There will be a replay of today's call and it will be available by webcast on the investors section of our website at ir.thirdcoast.bank. There will also be a call replay available until October 29 and more information on how to access the replay features was included in yesterday's earnings release. Please note that the information reported on this call speaks only as of today October 22, 2026, and therefore you are advised that time sensitive information may no longer be accurate at the time of replay, listening or transcript reading.

In addition, the comments made by management during this call may contain forward looking statements within the meaning of the United States federal securities laws. These forward looking statements reflect the current views of management. However, various risks, uncertainties and contingencies could cause actual results, performance or achievements to differ materially from those expressed in the statements made by management. The listener or reader is encouraged to read the annual report on Form 10-K and other filings with the SEC to better understand those risks, uncertainties and contingencies. Today's discussion will also include the proposed merger with Great Plains, Bancshares. This call does not constitute an offer to sell or a solicitation of an offer to buy any securities or a solicitation of any vote or approval. Third Coast intends to file a registration statement on form S-4 that will include a joint proxy statement prospectus. And investors are encouraged to read it when it becomes available, as it will contain important information about the proposed transaction. The comments made today will also include certain non-GAAP financial measures. Additional details and reconciliation to the most directly comparable GAAP financial measures were included in yesterday's earnings release, which can be found on the Third Coast website. Now I would like to turn the call over to third Founder, Chairman, President and CEO, Mr. Bart Caraway. Bart? .....................................................................................................................................................................................................................................................................

Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. Thank you, Natalie. And good morning, everyone. The third quarter was another healthy quarter for Third Coast and importantly, one that demonstrates the underlying strength of our franchise. Reported earnings included $3.2 million in merger related expenses, which affected non-interest expenses and net interest margin. John will walk through those items in more detail in just a moment. But when you look through those items, I believe the underlying performance of the franchise remains solid. There are a few things I'd point to. First, I'm encouraged by the continued momentum we're seeing in Treasury Management. The team continues to add customer relationships and generate a steady source of deposits over the past 12 months, non-interest-bearing deposits increased 60.3% compared with 35.5% growth in total deposits. For us, that's really about continuing to deepen customer relationships and build a stronger core funding base. Second, we're also seeing strong loan activity. Gross loans ended the quarter at approximately $5.5 billion. During the quarter, we sold approximately $87 million of loans through our securitization program. Excluding that sale, loan growth exceeded $144 million. That underlying growth is consistent with the pipelines we discussed with you last quarter and gives us continued confidence in the strength of customer demand across our markets. Third, credit remained stable. We recorded net recoveries during the quarter. Audrey will provide some additional detail on the portfolio in a few minutes. And fourth, tangible book value per share reached $33.31, another new high for the company. We view the continued growth in tangible book value as an important measure of the long term value we're building for our shareholders. When you put these things together, I believe they tell a pretty straightforward story about where we are today. We're continuing to grow the company, strengthen our customer relationships, and build value while also positioning Third Coast for the next stage of growth. And that brings me to Great Plains. Earlier this month, we announced our agreement to merge with Great Plains Bancshares, parent company of Great Plains National Bank. The combination will expand our presence in Dallas, establish our entry into Oklahoma, and is expected to create a franchise of approximately $9 billion in assets. We view Great Plains as an extension of the strategy we've been executing. We remain focused on disciplined

growth, strong customer relationships, thoughtful balance sheet management, sound credit fundamentals, and ultimately building a franchise, franchise capable of producing durable long term earnings. We feel good about the progress we're making, both in performance of the core bank today and in what we're building for the future. With that, I'll turn the call over to John to walk through the financial results and provide additional details on the quarter. John? ..................................................................................................................................................................................................................................................................... R. John McWhorter Senior Executive Vice President & Chief Financial Officer, Third Coast Bancshares, Inc.

Thank you, Bart, and good morning, everyone. As Bart mentioned, our third quarter results included a few items that are important to understand when looking at the quarter over quarter comparison. I'll spend some time on those items and provide additional detail on the underlying performance of the business. Net income for the third quarter was $19 million compared to $22 million in the second quarter and $18.1 million in the third quarter of 2025 and diluted earnings per share was $0.93 compared to $1.08 rate last quarter and $1.30 in the same period last year. However, excluding the $3.2 million of merger related expenses, adjusted net income was approximately $21.6 million or $1.06 per diluted share. Net interest income was $59.5 million compared to $60.3 million in the second quarter and $50.8 million in the third quarter of last year. Net interest margin was 3.7% and would have been 3.74% without the accelerated accretion compared with 3.83% last quarter. On loans, gross loans ended the quarter at approximately $5.5 billion, an increase of $57 million from year. However, that reported number includes the impact of approximately $87 million of loans sold through our securitization program during the quarter. Excluding that sale, underlying loan growth exceeded $144 million. As we discussed last quarter, securitization has become a part of our broader balance sheet and capital management strategy, and we expect to close a new securitization in the fourth quarter as well. On the funding side, total deposits ended the quarter at $5.9 billion, an increase of $69 million from June. Non-interest-bearing demand deposits increased approximately $78 million to $721 million and represented 12.2% of total deposits compared with just 11% at June. As Bart noted, the longer term trend of non-interest-bearing demand deposits is also encouraging. Average cost of deposits for the quarter was 3.09%, up just four basis points from the second quarter, while remaining 47 basis points below the third quarter of last year. Our reported efficiency ratio was 63.1% and as adjusted was 58.63% compared with 56.5% last quarter. The sequential comparison reflects both the merger related and other non-recurring items, as well as the approximately $3.5 million gain on the sale of the factoring business that benefited the second quarter non-interest income. We continue to build book value during the quarter. Book value per common share increased to $36.53 while tangible book value per common share reached a new high of $33.31 compared with $33.08 at June 30 and $30.91 a year ago. Finally, in case you missed it, we added a new table to our earnings release as something investors have asked for in the past, which is a breakout of our merger related expenses. And we also broke out the second quarter gain realized on the sale of our factoring business. This table shows adjusted ROA and ROE and also shows that by some measure it was our best quarter ever. It also shows that we have consistently grown net income for all reported periods. Overall, while several items affected the quarter over quarter comparison, we continue to see strong loan demand progress in our funding mix and continued growth in shareholder value.

With that, I'll turn the call over to Audrey to discuss asset quality. ..................................................................................................................................................................................................................................................................... Audrey A. Spaulding Senior Executive Vice President & Chief Credit Officer, Third Coast Bancshares, Inc. Thank you, John, and good morning, everyone. Credit performance remained stable during the quarter and overall portfolio performance remains consistent with our expectations. Non-performing loans ended the quarter at approximately $29 million, compared to $27.1 million in June. As a percentage of total loans, non-performing loans were 0.53%, compared with 0.50% last quarter and 0.52% a year ago. While we experienced a slight increase in the quarter, the overall ratio remains relatively consistent with recent periods. The increase in non-performing loans was primarily due to the placement on non-accrual of three SBA loans totaling approximately $2.3 million. This increase was partially offset by paydowns on non-accruals and four small loans which were placed back on accrual. It is also noteworthy that over 45% of our total non-accrual loans are fully SBA guaranteed or cash secured. We recorded net recoveries of $27,000 during the quarter, marking our third consecutive quarter of net recoveries. We have recorded net recoveries of $182,000 year to date. Provision for credit losses totaled $540,000 during the quarter, and the allowance for credit losses increased to $54.4 million, representing 0.99% of total loans. Our loan portfolio remains well diversified across industries, markets and borrower relationships. Portfolio allocations remain generally consistent with the prior quarter, with commercial and industrial loans representing 43% of total loans and construction development and land loans representing 16%. While owner occupied CRE was 11% and Non-owner occupied CRE was 18%. Overall, we continue to feel good about the credit profile of the portfolio. As we grow, our teams remain focused on disciplined underwriting, appropriate loan structures and proactive portfolio management. The consistency we're seeing in credit performance, even as the balance sheet continues to grow, reflects the same disciplined approach we've discussed with you throughout the year. With that, I'll turn the call back to Bart. Bart? ..................................................................................................................................................................................................................................................................... Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. Thank you, Audrey. As we look ahead, we believe Great Plains represents an important next step in building a stronger, more valuable Third Coast franchise. First and foremost, the transaction has the potential to transform our funding profile. Great Plains brings a granular, relationship based core deposit franchise that strengthens the commercial banking platform we have built at Third Coast and gives us greater capacity to support continued growth. When you pair that stronger funding base with the scale and capabilities we're bringing together, we believe it creates an opportunity for more durable earnings and long term stakeholder value. Our focus isn't simply on becoming a bigger bank. It's building a better bank. And as the banking landscape continues to evolve, we we believe there is meaningful value in building a Texas headquartered bank of scale with the talent, capabilities and relationship banking culture to compete. That kind

of franchise is increasingly difficult to replicate. Before we open the call to questions, I want to thank our employees for their continued commitment to our customers and to Third Coast and our customers and shareholders for the trust they place in us. We do not take that trust for granted and will continue to work to earn it in every way. With that, I'll turn the call back over to the operator.

Michael Rose Analyst, Raymond James Financial, Inc. Q

Hey, good morning, guys. Thanks for taking my questions. I just wanted to kind of get a better understanding of the margin dynamics this quarter. You know, typically when you have a securitization, you get a pretty meaningful boost. But you were down kind of 13 basis points. It looks like it was in the securities portfolio and I saw the balances grew. So maybe you added some yields were down. If you can just kind of walk us through kind of what happened this quarter, I think you'd guided to flat to up. So with the securitization, I would've thought that we would have seen that up. So if you could just walk us through all that would be great. Thanks. .....................................................................................................................................................................................................................................................................

R. John McWhorter Senior Executive Vice President & Chief Financial Officer, Third Coast Bancshares, Inc. A

Sure. So there's a lot, Michael, that I can say about the margin for this quarter. It certainly was a little bit of a surprise to us. On a more positive basis, we're definitely going to be up in the fourth quarter. So several points there on the margin I would point out that for the quarter, we were considerably better each consecutive month. In other words, July was the low point for the quarter and we would have expected it to be a little bit better because of the securitization. But that one, we were selling loans off the balance sheet that we had already amortized most of the fee income. So there were very few fees that we picked up from that one. The one that we're doing in the fourth quarter should be more material where we actually see a difference where this one we did not in the securities portfolio because we did the securitization early in the quarter. This one had a little bit lower yield than the existing portfolio. So it did drag it down a little. But then of course, late in the quarter when rates went up, all of those asset backed securities that we have on the books are floating rate. So I would expect an increase in the yield in securities for the quarter. Our non-interest-bearing demand is going to continue to be a nice tailwind. So if you look at the quarterly average non-interest bearing demand, it was I think $654 million average for the

quarter where period end was $721 million. So a pretty significant difference. And we're still at about those levels today. So where last quarter, we sold assets early in the quarter. It's going to be a little bit different this quarter that our non-interest bearing demand is up. Loans so far through today are up $80 million for the month. So it looks like we're going to have loans that are being funded by non-interest bearing demand. The rate increase, we are a little bit asset sensitive, so I'm a lot more optimistic about the fourth quarter than the third quarter was just kind of quirky that that I certainly wouldn't have expected the decline and a little bit of it was amortization of premiums on the Keystone portfolio. We didn't have many loans booked at a premium, but there were a few and unfortunately some of them paid off at the same time. So we had to amortize those premiums which which made a bigger difference too. So it just happened to be one of those quarters where everything seemed to be going in the wrong direction. And I think those will reverse themselves for the fourth quarter. .....................................................................................................................................................................................................................................................................

Michael Rose Analyst, Raymond James Financial, Inc. Q

I'm not trying to pin you down here, John, but as we think about the fourth quarter and the dynamics that you just laid out, you know, the four basis points you talked about earlier, the growth that you just mentioned, the NIB mix moving higher. How should we think is the starting point, you know, for the fourth quarter, you know, in the context that the margin increase through the third quarter? Thanks. .....................................................................................................................................................................................................................................................................

R. John McWhorter Senior Executive Vice President & Chief Financial Officer, Third Coast Bancshares, Inc. A

Michael Rose Analyst, Raymond James Financial, Inc. Q

Okay, perfect. And maybe one for you, Bart. You know, obviously, if you back out the securitization underlying growth close to the $145 million that's above the guide, John. You just mentioned that loans are up about $80 million so far this month. You're going to be adding the New Deal. You know, just how should we think about kind of pre and post deal loan generation, you know, kind of as we move forward? Is that is that prior target, you know, still what we should expect or should it be potentially something higher? Thanks. .....................................................................................................................................................................................................................................................................

Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. A

No, I think we're going to probably stay on target. There's a lot of dynamics to that. But we do have some teams that joined us at Third Coast that are ramping up, and I think that's reinforced the pipeline. At the same time, you know, our focus is going to be on integrating Great Plains and spending time with them. I do think there's some upside in their production in that they have some

larger customers that would benefit from more products that we have. But I think all in all, we probably are sticking with the same guidance that we've had. I think it's going to be fairly consistent and a little bit of that too, with rates going up may put a little bit of damper on on some of the loan production. I think that's going to be offset by how robust our pipelines are. So evening everything out. I'm sticking to the same guidance we've had for the last, you know, three or four months. .....................................................................................................................................................................................................................................................................

R. John McWhorter Senior Executive Vice President &Chief Financial Officer, Third Coast Bancshares, Inc. A

Yeah. And Michael, just maybe a little more color from my perspective. You know, last quarter, I would have thought that we could have done the securitization and still growing $100 million and it was $56 million. So we were off a little bit there. I would say the same thing for the fourth quarter that we can do a securitization and still grow in that $100 million range. But the difference is going to be we're not going to close it early in the quarter like we did the last one. It would be much later in the quarter and not impossible that it would push to the first quarter. But but most likely it's going to be a December sort of transaction. We we kind of have it teed up and should be ready to go on it. And we're waiting to see what the growth for the quarter looks like. But it's been strong enough lately that it's kind of just the best guess at this point. .....................................................................................................................................................................................................................................................................

Michael Rose Analyst, Raymond James Financial, Inc. Q

R. John McWhorter Senior Executive Vice President &Chief Financial Officer, Third Coast Bancshares, Inc. A

Yeah. So we've been real happy with fee income initiatives lately. The Treasury Management Group continues to do well for for this quarter. Specifically, the differences versus prior quarters were we had more swap fees and we had more loan fee. And those are a little harder to forecast. Although with the pipelines being strong, those those numbers should continue to be strong. The swap fees, I mean, they're they're customer dependent. It's just hard to say. And then the other piece that we have this quarter that we haven't had previously is this trailing revenue stream from the sale of our factoring company. And that was $150,000 or thereabouts for the quarter that that number shouldn't go down unless those loans pay off. And if we refer more deals, it could go up. So we're pretty optimistic about fee income. And, you know, again, tend to be just a little bit lumpy based on loan volume being that a lot of that loan fee related. But we feel pretty good about the quarter. .....................................................................................................................................................................................................................................................................

Michael Rose Analyst, Raymond James Financial, Inc. Q

Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. A

Hannah Wynn Analyst, Keefe,Bruyette & Woods,Inc. Q

Hi. Good morning, guys. Thanks for taking my question. I wanted to start on the hiring side. I know you guys have continued to invest in experienced lenders and hired five new hires last quarter. Just curious how the hiring progress this quarter was and when those newer teams are expected to ramp up in the process and when we should expect a more meaningful contribution to growth. .....................................................................................................................................................................................................................................................................

Bart O. Caraway Founder, Chairman, President & Chief Executive Officer, Third Coast Bancshares, Inc. A

Yeah, well, we've the teams that have come on teams that we've known for a long time and I think I'll give credit to the management team have gotten very good at kind of feathering in experienced team members aligned with their production, so that they get profitable very quickly. And indeed, I think the team's just gotten better and better at that. But these experienced bankers come with high quality customers that they are bringing on early. So I expect each one of them to get to profitability much faster than in the past. And indeed, some of them are already there. At this point I think they're already contributing to the pipeline. Maybe the last one is coming is we feel like it's going to be very strong as well. And at this point, I think we've we've gotten the people that we'll probably have for

for this year. Maybe if there's a lucky surprise, we another one. But for the most part, it's instead of volume, it is very targeted in surgical hiring. People that are coming on board, fewer numbers, but much bigger pipelines. And so I think we're really pleased the way we've managed it. It's not been a drag on the earnings like in the past. We've hired large teams and it took a while for them to ramp up. I think these are teams that are coming on that make almost an immediate impact and sometimes they're profitable within the first month they come on. .....................................................................................................................................................................................................................................................................

Hannah Wynn Analyst, Keefe,Bruyette & Woods,Inc. Q

R. John McWhorter Senior Executive Vice President & Chief Financial Officer, Third Coast Bancshares, Inc. A

Hannah Wynn Analyst, Keefe,Bruyette & Woods,Inc. Q

R. John McWhorter Senior Executive Vice President &Chief Financial Officer, Third Coast Bancshares, Inc. A