Bank of New York Mellon Corp. (BK) grew its first-quarter profit to $625 million, or 50 cents a share, as the company reaped benefits of having assets under its custody grow 14% over last year. Earnings for the quarter compare to income of $559 million, or 46 cents a share, during the first quarter of 2010. The company’s revenue rose 9% year-over-year, hitting nearly $3.65 billion in the first quarter compared to about $3.34 billion a year ago. Even still, the company’s stock fell Tuesday morning, with the bank’s profit falling below the average analyst estimate of earnings per share in the 57-cent range, according to Yahoo! Finance. By the end of the first quarter, the largest trust bank in the world had $25.5 trillion in assets under its custody and administration up 14% from a year earlier. Assets under management — excluding securities lending assets — hit $1.2 trillion, an 11% increase over last year. “A fundamental strength of our business model is the ability to rapidly grow capital and generate a high return on it,” said Robert Kelly, the bank’s chairman and CEO. “Specifically, in the first quarter of 2011, our capital grew at an annualized rate of 28% and we generated a 21% return on it. Over time this provides us with superior flexibility to invest in our businesses and return capital to our shareholders.” Write to Kerri Panchuk.