All Share Index (ASI) and Market Capitalization declined by 13 percent to close at 23514.04 points and N8.09 trillion respectively at the end of the trade session on January 15. The huge drop in the Index, representing a 3-year low, led to the introduction of the Index Circuit Breakers Rule. While this policy measure may prevent huge losses in the stock market, rising concerns about macroeconomic stability in Nigeria may significantly increase the level of volatility in the stock market. This may have substantial adverse implications for investors in the Stock Exchange.