Every B2B company has to find a balance between customer acquisition and existing account growth. Many are finding tremendous opportunity for revenue in the latter and shifting their focus to the accounts with the most growth potential, but it's not a simple transition. eMarketer's Jillian Ryan spoke with Mark Kovac, global head of Bain & Company's Commercial Excellence Group, about what measures need to be taken by B2B marketers to drive more revenue from a small subset of existing accounts.