(Reuters) - BlackRock Inc , the world's largest asset manager, reported a 23% drop in quarterly profit, as investors pulled money out of its marquee funds and preferred cash management services, while costs rose amid a global economy hit by the coronavirus pandemic.The New York-based company's net income fell to $806 million, or $5.15 per share, in the first quarter ended March 31, from $1.05 billion, or $6.61 per share, a year earlier.The company ended the quarter with $6.47 trillion in..