How interest rates affect everything

Interest rates are the gravity of finance. They affect everything — mortgages, stocks, bonds, real estate, car loans, savings yields, currency exchange, commodity prices — often in ways that aren't obvious at first glance. A change in the Fed's target rate eventually touches almost every financial decision you make.

Bonds: the direct link

Bond prices move inversely to interest rates. When rates go up, existing bond prices go down (because new bonds pay more and old bonds look less attractive). When rates go down, bond prices go up. This is why bond funds can lose money during rising-rate environments even though bonds are 'safer' than stocks.

Mortgages: the personal impact

Mortgage rates don't exactly track the Fed funds rate — they follow the 10-year Treasury yield more closely. But the Treasury yield and the Fed rate move in the same general direction. When rates rise, mortgages get more expensive, which cools housing demand, which can eventually cool home prices. When rates fall, mortgages get cheaper and demand rises.

Stocks: the indirect impact

Higher interest rates hurt stock prices for a few reasons. First, borrowing gets more expensive for companies, cutting into profits. Second, bonds become more competitive with stocks as income producers, drawing money out of equities. Third, the present value of future cash flows gets discounted more heavily. Growth stocks — whose value is based on far-future earnings — are especially sensitive.

Your practical takeaway

You don't need to predict interest rate changes. You just need to understand the direction of travel and adjust: lock in cheap mortgage rates when they're low, take advantage of high savings yields when they rise, and don't be surprised when your bond fund drops 10% during a tightening cycle. Interest rates explain more of market movement than almost anything else, and they're the least reported-on major variable in financial media.