Northern Trust Corporation (NTRS)

The first half is custody and servicing for pension funds, insurers and sovereign funds: record keeping, settlement, reporting. Fees scale with assets under custody, so income grows with markets and carries almost no credit risk, and scale matters because platform costs are largely fixed.

The second half is managing family wealth, where the bank handles not only investments but trusts, tax planning and passing capital to heirs. Such relationships run across generations and are rarely broken. A third source is interest on client balances, which rises with rates. Risks: falling markets, fee pressure and the cost of the technology platform. The company pays a dividend.