When the Federal Open Market Committee (FOMC) changes the interest rate, it impacts both the economy and the stock markets because borrowing becomes either more or less expensive for individuals and businesses.
Any impact on the stock market to a change in the interest rate changes is generally experienced immediately, while, for the rest of the economy, it may take about a year to see any widespread impact.
Higher interest rates tend to negatively affect earnings and stock prices (with the exception of the financial sector).