The paper examines the impact of deposit rates on savings, lending rates on credits and market capitalization of Nigerian Exchange group limited from 1985 to 2021, using co-integration and vector error correction approach. The specific objectives were to estimate the short-and long-run association as well as the error correction mechanism of lending interest rate and deposit interest rate and stock market capitalization in Nigeria. The outcome of the exercise validated the hypothesis of financial liberalisation theory that deposit rates on savings, lending rates on credits on market capitalization of Nigerian Exchange group limited. Deposit interest rate and lending interest rate have significant explanatory power for stock market capitalization, which is consistent with our expectations in line with financial liberalization theory in Nigeria. The regulatory body should mandate banks to channel their mobilised savings to investors in form of loans at reasonable interest rate. Hence, the pointer should be to identify those constraints and bottlenecks that are making it difficult for banks to make loans available to investors. The issue of high interest rate with hidden transaction costs must be vigorously addressed by the monetary authorities; Monetary authorities should pursue policies that will encourage the saving culture of the people. This could be done by increasing the deposit rate which would lure people to deposit their money in banks thereby increasing the supply of loanable funds. This would lead to a fall in interest rate and eventually rise in investment in stock market development.