BlackRock takes aim at CEOs serving on other companies' boards

NEW YORK (Reuters) - BlackRock Inc is stepping up opposition to U.S. CEOs who sit on more than one corporate board beside their own, arguing that working as a director takes increasingly more time, a report from the world's largest asset manager showed on Tuesday.BlackRock cast votes against 94 chief executives running for re-election to corporate boards outside of their own in this year's proxy season, up from 32 last year, according to the report. The uptick reflects BlackRock's concerns..