BlackRock Inc (BLK.N), the world's biggest asset manager, reported an 8.6-per-cent rise in quarterly profit on Monday, helped by higher fees.

The company's index-tracking exchange-traded funds have been growing at a record pace.

But the asset manager has been trying to restructure its actively managed stockpicking to thrive in a business that has seen its growth prospects slashed as investors move to low-cost funds.

The company has been cutting fees and has recently launched new bond ETFs in efforts to lure more investors to its products from traditional debt markets.

BlackRock ended the quarter with US$5.69 trillion in assets under management, up from the preceding quarter, when managed assets totaled US$4.89 trillion.

The company's net income rose 8.6 per cent to US$857 million in the second quarter.

In the most recent quarter, the company's iShares ETF business took in US$73.8 billion in new money, up from US$15.7 billion, a year earlier.

Net investment in fixed-income securities totaled US$42.92 billion. BlackRock attracted total "long-term" net flows of US$103.62 billion in the quarterly period.