Johannesburg has been rated among the Top 50 commercial cities in the world – despite a dismal score for knowledge and information flow. 

Coming in at 47 of the world's top 50 global centers of commerce, Johannesburg scored well in most of the other criteria of legal and political frameworks; economic stability; the ease of doing business; financial flows; and business centre capabilities,.
However, it scored substantially below the other 49 cities for knowledge creation and information flow, with a paltry 3,22.
This compares to winning city, London, which scored 52,72 for knowledge and information; and next worst-ranked Dubai with its 4,24 (Dubai ranked 37 overall).
Johannesburg's poor ranking is becaues the city boasts few researchers, patents and tradements. It also has few higher learning centres and medical schools.