You can determine whether a company have a sizeable market share by comparing sales figures in the income statement to sales of other companies within the same industry. (myfinancekits.com)
Comparing gross margin figures for multiple companies within the same industry can also be useful in signaling which businesses have the most efficient operations. (fool.com)
But investing all your money in companies within the same industry is not a true diversification. (myfinancekits.com)