Nvidia to join Dow Jones Industrial Average, replacing Intel

Fakenomics. What sort of benchmark is provided by an index that drops poor performers and replaces them with rising ones?

Interesting question, and surely you're right, there's a limitation in that specific benchmark as it is functioning like raisin picking and doesn't reflect other big parts of the economy. But of course much more important with this one is the use as an ID card of an economy on a global scale. Such indices reflect the top structure, the market volume of an economy and the present and near future development also can somehow be read, when companies 'leave' and other companies 'enter' an index. And of course your question is also answered by the fact that there are also manybother benchmarks which contain the companies below the top ones and again other benchmarks that contain only the poor performers or only the fast rising ones.