. . . [T]he nature of stock markets and the economies in Africa revealed the reasons for non-causal relationships between stock markets and economic growth in Ghana and Nigeria. The problem of African stock markets is the domination by a single sector, and the often monoproduct economy. Often, the stocks of this sector that account for the greater percent of the GDP are not listed in the domestic stock market, hence, a divorce between the actual performance of the stock market and economic growth. In Ghana, only AngloGold Ashanti, accounts for 70% of market capitalization (Osaze, 2007) while in Nigeria, over 60% of the total market capitalization is accounted for by the Banking sector. The oil and gas sector of the economy of Nigeria and the agricultural sector (cocoa) of that of Ghana are not in their stock markets.
From a paper by Osamwonyi & Kasimu, "Stock Market and Economic Growth in Ghana, Kenya and Nigeria" (International Journal of Financial Research, April 2013).