Our five top banks control 85% of all current accounts - that's Lloyds, RBS, HSBC, Barclays and Santander.
They use that to sell us other things: 88% of current account customers have savings accounts with the same bank, 53% have credit cards with the same bank and 42% have their bank's Cash ISA.
Banks earn £8.3bn in revenue from our current accounts, or £152 per account. Half of the income comes from pocketing the interest they make on our cash.
Most of us have a suspicion that we ought to switch to a better current account. Banks say only 7% of us bother to switch each year. Others put the figure as low as 3%.
Compare that to the 26% who switch energy provider or phone company.
In spite of the hold these banks have on us, we're frightened of taking our business elsewhere.
But maybe, on Monday, things could start to change.
Sir John Vickers' Independent Commission on Banking is due to recommend ways of loosening the banks' grip on our money - by beefing up competition.