Savings Deposit
Also known as: Savings account, Instant-access account, Tagesgeld
The product almost everyone owns and almost nobody analyses: a loan you make to a bank, repayable on demand, at a rate the bank chooses.
- Asset class
- Money markets (retail bank funding)
- Instrument type
- Demand deposit
- Traded
- Not traded — a contract with one bank
- Typical users
- Every household; corporate treasuries at scale
1 · SnapshotThe one idea to remember
2 · BeginnerWhat is it, really?
A savings deposit is a loan you make to a bank. The bank owes you the money back, usually on demand, and pays interest for the use of it in the meantime. That is the entire product.
Two things follow from "it is a loan", and both surprise people:
- The money is not in a vault with your name on it. The bank lends it on. What you hold is a claim on the bank, not a box of cash.
- The rate is set by the bank, not by contract. It can be changed at any time, and historically it rises slowly when policy rates rise and falls quickly when they fall.
What makes the deal work anyway is deposit insurance: in most developed jurisdictions a state-backed scheme guarantees balances up to a per-bank, per-person limit. Below that limit the bank's credit quality is genuinely somebody else's problem. Above it, it is yours.
3 · IntermediateHow it works in practice
The rate you are actually paid
- Deposit beta is the industry term for how much of a policy-rate move is passed on. Betas of 0.2–0.5 on instant-access savings are ordinary — a 4% policy rate can sit alongside a 1% savings rate for years.
- Back-book pricing: new customers get the advertised rate; existing balances quietly stay on an older, lower one. The gap is a large and deliberate source of bank margin.
- Compounding frequency matters less than the headline, but it matters: use the nominal-to-effective converter to compare accounts quoting monthly and annual interest.
The real return is the only one that counts
Nominal safety is not real safety. A 2% deposit rate against 4% inflation loses 2% of purchasing power a year with complete certainty — the one loss no risk model flags because the nominal balance never falls. The real-return calculator makes the size of it visible.
Deposit insurance in practice
| Feature | How it typically works |
|---|---|
| Limit | Per depositor, per institution, per scheme — not per account |
| Joint accounts | Usually counted per holder, doubling the effective cover |
| Brands | Several brands can share one banking licence and one limit |
| Payout | Days to weeks in modern schemes; the money is frozen meanwhile |
4 · AdvancedPricing & valuation
Why the deposit is the bank's most valuable liability
Deposits are contractually repayable on demand but behave as long-term funding — households do not move them for a few basis points. Banks model this as a non-maturity deposit with an assumed behavioural life, replicated with a portfolio of fixed-rate assets:
The value of the deposit franchise is the discounted spread between what the bank earns on the money and what it pays for it, over the balance's assumed life. That is the number bank valuations turn on.
The assumption that breaks
- The replicating portfolio assumes deposits are sticky and that duration risk is hedged. Get the first right and the second wrong and rising rates produce unrealised losses on the asset side against liabilities that can leave instantly.
- Digital banking compressed the run timescale from days to hours: balances now move at the speed of an app notification, while the asset side still liquidates at the speed of a bond market.
- Uninsured deposits are the fast money — concentrated, professionally managed, and the first to leave. The insured/uninsured mix is the single most informative line in a bank's funding disclosure.
Where it sits in the product spectrum
Moving out from the deposit: a certificate of deposit trades access for a fixed term and rate; a money market fund trades the insurance for diversification and market-linked yield; a T-bill replaces bank credit with sovereign credit. Each step exchanges one specific comfort for one specific improvement.
The formulas above are standard textbook formulations, simplified for teaching. They explain the mechanism — they are not a valuation tool, and they will not reproduce a dealer’s price.