4 letters:
banc, bank, dank, hank, jank, lank, mank, rank, sank, tank, yank, zank

5 letters:
afanc, banke, blanc, blank, branc, brank, chank, clank, cranc, crank, danke, drank, flanc, flank, franc, frank, hanke, ibank, janke, klank, krank, manke, mbank, plank, prank, ranck, ranke, sanke, shank, skank, slank, spank, stank, swank, tanke, thank, trank, tranq, ubank, vanke, yanke

6 letters:
akbank, albank, ambank, ananke, banque, blanck, blanke, dahnke, embank, enrank, flanke, franck, franke, imbank, inbank, jahnke, kalank, manque, nubank, phranc, planck, psbank, s-bank, s-rank, schank, selank, shrank, stanke, tanque, unbank, yahnke

7 letters:
baybank, biobank, burbank, crywank, cutbank, deblanc, disrank, ecobank, firbank, fogbank, francke, gedanke, genbank, gosbank, keybank, lablanc, leblanc, maybank, milbank, nadbank, nedbank, neobank, nonbank, outrank, rakbank, schanck, schlank, schrank, stahnke, unthank, veranke

8 letters:
agribank, antitank, arranque, calanque, citibank, claybank, colebank, cryobank, dadivank, databank, dbs bank, drugbank, edgerank, equibank, eurobank, eximbank, fernbank, fishtank, forerank, gas tank, girobank, halkbank, kiwibank, landbank, lanfranc, m60 tank, medibank, merabank, metabank, millbank, minibank, non-bank, omnibank, outdrank, outflank, overbank, overrank, petanque, rabobank, riksbank, sandbank, sberbank, schranke, seedbank, seekrank, snowbank, softbank, stopbank, swedbank, teletank, treebank, triptank, tymebank, veribanc

9 letters:
alfa-bank, ameribanc, anti-tank, army tank, axis bank, bellcrank, brookbank, caixabank, cantabank, charabanc, chinabank, clickbank, clydebank, coin bank, datenbank, denizbank, earthbank, fish tank, flag rank, food bank, foreshank, gangplank, hdfc bank, interbank, kakaobank, kutxabank, lead bank, left bank, marchbank, metrobanc, metrobank, montblanc, multibank, phishtank, piggybank, primebank, riverbank, soil bank, superbank, volksbank, west bank

10 letters:
agent bank, ameriabank, blood bank, bundesbank, centerbank, cloud bank, coin blank, creditbank, crookshank, cruikshank, deathspank, eisschrank, front-rank, hackerrank, holderbank, icici bank, landesbank, lower rank, mali franc, mont blanc, mountebank, penny bank, piggy bank, pointblank, privatbank, reichsbank, right bank, scotiabank, sperm bank, state bank, thermotank, think-tank, think tank, togo franc, unitedbank, vietinbank, water tank, world bank

11 letters:
benin franc, commerzbank, congo franc, countersank, cruickshank, double-bank, elektrobank, floridabanc, gabon franc, gazprombank, handelsbank, higher rank, kredietbank, laenderbank, member bank, nacotchtank, nationsbanc, nationsbank, niger franc, oyster bank, pinot blanc, point-blank, septic tank, social rank, solarisbank, swiss franc, vereinsbank, vietcombank

12 letters:
central bank, chars-a-banc, draw a blank, french franc, kasikornbank, kontrollbank, panther tank, prankvsprank, quarteurlanc, republicbank, reserve bank, russian bank, rwanda franc, savings bank, storage tank

13 letters:
astrodatabank, belgian franc, burundi franc, chadian franc, gasoline tank, merchantsbank, merchant bank, military rank, national bank, nationsbanc's, pedro francke, vertical bank

14 letters:
blankety-blank, cameroon franc, djibouti franc, gefrierschrank, home loan bank, kleiderschrank, luke greenbank, raiffeisenbank, rank-into-rank, taxonomic rank

15 letters:
commercial bank, hypovereinsbank, industrial bank, jack brooksbank, ratchet & clank, sauvignon blanc, vnesheconombank

16 letters:
insignia of rank, lucas cruikshank, luxembourg franc, madagascar franc, main battle tank, middenstandsbank

17 letters:
full service bank, ivory coast franc, upper volta franc

18 letters:
burkina faso franc

19 letters:
cote d'ivoire franc, genossenschaftsbank, kotak mahindra bank, mutual savings bank

20 letters:
endorsement in blank, federal reserve bank, federal savings bank, punjab national bank

23 letters:
kliment voroshilov tank

30 letters:
central african republic franc