RANKING ·
Largest net interest margin improvement in Iowa
194 of 227 banks in Iowa that filed for the quarter ended June 30, 2026 are ranked. At least $100 million in total assets and a comparable quarter a year earlier. Institutions with equal values share a rank. Source: FDIC quarterly financial data.
| Rank | Institution | Headquarters | Net interest margin, change over 12 months | Total assets |
|---|---|---|---|---|
| 1 | Bank | Wapello, IA | +109 bps | $217 million |
| 2 | Bridge Community Bank | Mount Vernon, IA | +94 bps | $141 million |
| 3 | Blue Grass Savings Bank | Blue Grass, IA | +84 bps | $225 million |
| 4 | Farmers State Bank | Waterloo, IA | +84 bps | $1.6 billion |
| 5 | Pioneer Bank | Sergeant Bluff, IA | +71 bps | $283 million |
| 6 | Farmers Trust & Savings Bank | Buffalo Center, IA | +71 bps | $423 million |
| 7 | Fnnb Bank | Newton, IA | +70 bps | $109 million |
| 8 | Security State Bank | Algona, IA | +70 bps | $110 million |
| 9 | First National Bank Ames, Iowa | Ames, IA | +66 bps | $1.1 billion |
| 10 | Midwest Heritage Bank FSB | West Des Moines, IA | +64 bps | $768 million |
| 11 | American Bank N.A. | Le Mars, IA | +64 bps | $533 million |
| 12 | Denver Savings Bank | Denver, IA | +64 bps | $251 million |
| 13 | Central State Bank | Coralville, IA | +63 bps | $419 million |
| 14 | Citizens State Bank | Monticello, IA | +63 bps | $594 million |
| 15 | Iowa State Savings Bank | Creston, IA | +63 bps | $277 million |
| 16 | Bellevue State Bank | Bellevue, IA | +63 bps | $188 million |
| 17 | American State Bank | Sioux Center, IA | +62 bps | $1.4 billion |
| 18 | Farmers State Bank | Northwood, IA | +61 bps | $221 million |
| 19 | Farmers & Merchants Savings Bank | Manchester, IA | +61 bps | $617 million |
| 20 | Citizens First Bank | Clinton, IA | +60 bps | $361 million |
| 21 | First State Bank | Lynnville, IA | +59 bps | $384 million |
| 22 | South Story Bank & Trust | Slater, IA | +58 bps | $624 million |
| 23 | Maynard Savings Bank | Maynard, IA | +58 bps | $108 million |
| 24 | The Home Trust & Savings Bank | Osage, IA | +57 bps | $288 million |
| 25 | Farmers Trust & Savings Bank | Earling, IA | +57 bps | $148 million |
| 26 | United Community Bank | Milford, IA | +55 bps | $290 million |
| 27 | Leighton State Bank | Pella, IA | +55 bps | $298 million |
| 28 | Grinnell State Bank | Grinnell, IA | +54 bps | $499 million |
| 29 | Northwest Bank | Spencer, IA | +53 bps | $3.0 billion |
| 30 | Security State Bank | Radcliffe, IA | +53 bps | $119 million |
| 31 | Marion County State Bank | Pella, IA | +53 bps | $629 million |
| 32 | United Bank & Trust Co. | Marshalltown, IA | +52 bps | $120 million |
| 33 | Farmers State Bank | Marion, IA | +52 bps | $1.1 billion |
| 34 | Bank Iowa | West Des Moines, IA | +51 bps | $2.3 billion |
| 35 | First Citizens Bank | Mason City, IA | +50 bps | $1.8 billion |
| 36 | Citizens State Bank | Sheldon, IA | +50 bps | $195 million |
| 37 | Kerndt Brothers Savings Bank | Lansing, IA | +49 bps | $347 million |
| 38 | Commercial Savings Bank | Carroll, IA | +49 bps | $349 million |
| 39 | Hills Bank and Trust Company | Hills, IA | +49 bps | $4.8 billion |
| 40 | Audubon State Bank | Audubon, IA | +48 bps | $155 million |
| 41 | State Bank & Trust Co. | Nevada, IA | +48 bps | $198 million |
| 42 | First Bank | Waverly, IA | +48 bps | $740 million |
| 43 | The State Bank of Toledo | Toledo, IA | +45 bps | $135 million |
| 44 | Primebank | Le Mars, IA | +45 bps | $801 million |
| 45 | First Central State Bank | Dewitt, IA | +45 bps | $772 million |
| 46 | Fidelity Bank & Trust | Dubuque, IA | +44 bps | $2.6 billion |
| 47 | Reliance State Bank | Story City, IA | +44 bps | $277 million |
| 48 | Premier Bank | Dubuque, IA | +44 bps | $358 million |
| 49 | Lincoln Savings Bank | Reinbeck, IA | +44 bps | $1.7 billion |
| 50 | Pinnacle Bank | Marshalltown, IA | +44 bps | $324 million |
| 51 | Danville State Savings Bank | New London, IA | +44 bps | $183 million |
| 52 | Farmers & Merchants Bank & Trust | Burlington, IA | +43 bps | $208 million |
| 53 | Security Savings Bank | Gowrie, IA | +43 bps | $194 million |
| 54 | Freedombank | Elkader, IA | +43 bps | $434 million |
| 55 | Central Bank | Storm Lake, IA | +42 bps | $2.3 billion |
| 56 | Nsb Bank | Mason City, IA | +42 bps | $461 million |
| 57 | West Bank | West Des Moines, IA | +42 bps | $4.0 billion |
| 58 | Farmers Savings Bank & Trust | Traer, IA | +42 bps | $213 million |
| 59 | Midstates Bank N.A. | Council Bluffs, IA | +41 bps | $654 million |
| 60 | Mount Vernon Bank and Trust Company | Mount Vernon, IA | +41 bps | $195 million |
| 61 | Cusb Bank | Cresco, IA | +41 bps | $812 million |
| 62 | Peoples Savings Bank | Wellsburg, IA | +40 bps | $189 million |
| 63 | Bank Midwest | Spirit Lake, IA | +40 bps | $1.3 billion |
| 64 | Farmers Savings Bank | Marshalltown, IA | +39 bps | $140 million |
| 65 | Cherokee State Bank | Cherokee, IA | +39 bps | $271 million |
| 66 | Bankiowa | Cedar Rapids, IA | +39 bps | $846 million |
| 67 | United Bank and Trust Company | Hampton, IA | +38 bps | $228 million |
| 68 | First Whitney Bank and Trust | Atlantic, IA | +37 bps | $288 million |
| 69 | United Bank of Iowa | Ida Grove, IA | +37 bps | $2.5 billion |
| 70 | Farmers Savings Bank | Wever, IA | +37 bps | $131 million |
| 71 | Houghton State Bank | Red Oak, IA | +36 bps | $205 million |
| 72 | Shelby County State Bank | Harlan, IA | +35 bps | $524 million |
| 73 | First Iowa State Bank | Albia, IA | +35 bps | $396 million |
| 74 | Maquoketa State Bank | Maquoketa, IA | +34 bps | $429 million |
| 75 | Savings Bank | Primghar, IA | +34 bps | $305 million |
| 76 | Templeton Savings Bank | Templeton, IA | +34 bps | $170 million |
| 77 | Raccoon Valley Bank | Perry, IA | +34 bps | $486 million |
| 78 | Iowa State Bank and Trust Company | Fairfield, IA | +33 bps | $352 million |
| 79 | Security Trust & Savings Bank | Storm Lake, IA | +33 bps | $266 million |
| 80 | First Security Bank and Trust Company | Charles City, IA | +33 bps | $538 million |
| 81 | Iowa Trust & Savings Bank | Emmetsburg, IA | +33 bps | $522 million |
| 82 | Visionbank of Iowa | Ames, IA | +33 bps | $896 million |
| 83 | Fairfax State Savings Bank | Fairfax, IA | +32 bps | $287 million |
| 84 | Ohnward Bank & Trust | Cascade, IA | +31 bps | $499 million |
| 85 | St. Ansgar State Bank | Saint Ansgar, IA | +31 bps | $182 million |
| 86 | Central State Bank | State Center, IA | +31 bps | $558 million |
| 87 | City State Bank | Norwalk, IA | +31 bps | $788 million |
| 88 | Corydon State Bank | Corydon, IA | +31 bps | $138 million |
| 89 | Pilot Grove Savings Bank | Pilot Grove, IA | +31 bps | $1.2 billion |
| 90 | First State Bank | Belmond, IA | +31 bps | $142 million |
| 91 | Security State Bank | Sutherland, IA | +31 bps | $492 million |
| 92 | Atkins Savings Bank & Trust | Atkins, IA | +31 bps | $172 million |
| 93 | New Albin Savings Bank | New Albin, IA | +30 bps | $351 million |
| 94 | Guthrie County State Bank | Panora, IA | +30 bps | $279 million |
| 95 | Mediapolis Savings Bank | Mediapolis, IA | +30 bps | $270 million |
| 96 | Farmers Trust and Savings Bank | Spencer, IA | +30 bps | $618 million |
| 97 | First Community Bank | Newell, IA | +29 bps | $116 million |
| 98 | Fnb Bank | Fontanelle, IA | +29 bps | $275 million |
| 99 | Union State Bank | Winterset, IA | +29 bps | $136 million |
| 100 | Bank Plus | Estherville, IA | +29 bps | $145 million |
Rankings sort one published measure; they are not an overall judgment of any institution. Methodology · All rankings