The loanable funds market brings together savers, who supply funds, and borrowers, who demand them. Their meeting point sets the real interest rate and the amount of private investment. Shift saving, investment demand, the government budget, and foreign capital to see which curve moves, then practice the national saving identity with the calculator.
The market starts at a 5.0% real interest rate with $500 billion lent and borrowed, all of it for private investment, and a balanced government budget. Dashed grey lines show the starting position once something moves.
Supply of loanable funds (SLF) comes from saving: private saving by households and firms, public saving when the government runs a surplus, and foreign saving that flows in. It slopes up because a higher real interest rate rewards saving.
Demand for loanable funds (DLF) comes from borrowers: firms that want to invest in capital, and the government when it runs a deficit. It slopes down because fewer investment projects pay off at a higher real interest rate.
Price on the vertical axis: the real interest rate. A change in the rate moves along the curves; a change in saving or investment plans shifts them.
National saving is the domestic source of loanable funds. Pick an AP-style preset or type your own numbers (in billions of dollars). The work is shown the way you would write it on the exam.
Savers lend and borrowers borrow, usually through banks and bond markets. The price of a loan is the real interest rate. Equilibrium sets the real interest rate and the quantity of loanable funds.
Supply comes from national saving plus foreign saving. More private saving, a bigger budget surplus, or an inflow of foreign financial capital shifts SLF right and lowers the real interest rate.
Demand comes from firms that borrow to invest and from a government that borrows to cover a deficit. An investment tax credit or business optimism shifts DLF right and raises the real interest rate.
Private saving is disposable income minus consumption. Public saving is the budget balance, T − G. A deficit is negative public saving, so it pulls national saving down.
Show a deficit as DLF shifting right (the government borrows) or as SLF shifting left (public saving falls). Both raise the real interest rate and lower private investment. AP accepts either if you label it.
The loanable funds market sets the real interest rate and both curves slope. The money market sets the nominal interest rate and has a vertical money supply set by the central bank. Pick the graph that matches the question.
Memorize which curve each event shifts. Then the real interest rate and private investment follow from the graph.
| Event | Curve and direction | Real interest rate | Quantity of loanable funds | Private investment |
|---|---|---|---|---|
| Households save more | Supply right | ↓ | ↑ | ↑ |
| Households save less (consumer spending up) | Supply left | ↑ | ↓ | ↓ |
| Government budget deficit (or bigger deficit) | Demand right, or supply left | ↑ | ↑ if drawn as demand right; ↓ if drawn as supply left | ↓ (crowding out) |
| Government budget surplus | Supply right, or demand left | ↓ | ↑ if drawn as supply right; ↓ if drawn as demand left | ↑ |
| Investment tax credit or business optimism | Demand right | ↑ | ↑ | ↑ |
| Business pessimism | Demand left | ↓ | ↓ | ↓ |
| Inflow of foreign financial capital | Supply right | ↓ | ↑ | ↑ |
| Outflow of financial capital | Supply left | ↑ | ↓ | ↓ |
| Business optimism and more saving at once | Demand right and supply right | Indeterminate | ↑ | ↑ |
AP-style multiple choice. Pick an answer to see the explanation.
The vocabulary for topic 4.7. Read the list, flip through flashcards, or quiz yourself. For every term in the unit, see the Unit 4 terminology guide.