BlackRock closed in on $6 trillion in assets under management as investors stormed into their index funds and the bull market in US stocks raged on, it said today. 

BlackRock is the world's biggest asset manager.

It reported an 8.2% rise in quarterly profit, beating Wall Street estimates as it attracted $96 billion into its funds, about half of that into relatively low-cost exchange-traded funds (ETFs). 

The increase in assets under management to $5.98 trillion, along with strong investment performance pushed up revenues by 14%. 

Index-tracking ETFs have gained popularity among investors in recent years and are responsible for the lion's share of the billions in cash that BlackRock pulls in annually. 

But they have become a source of consternation to traditionalist stock pickers who typically charge higher fees. 

The asset manager's third-quarter profits spiked to $947m, or $5.78 per share, in the quarter from $875m, or $5.26 per share, a year earlier. 

Excluding items, the company earned $5.92 per share. Analysts expected $5.56, according to Thomson Reuters I/B/E/S. 

Revenues from the company's smaller technology business rose 15% to $175m during the quarter. 

"It's going to be one of our biggest competitive advantages," the company's chief executive Laurence Fink told Reuters.

BlackRock's ability to choose winning investments has improved, with 82% of assets in its funds ranking in the top half of their categories for three-year performance, according to recent research. 

By BlackRock's reckoning, more than $8 in $10 that clients hold across its active funds are in products that are beating their benchmarks over three years. 

The "actively managed" funds gathered $5.8 billion for BlackRock during the quarter, and helped the company book more fees for beating performance targets. 

Performance fees rose by $133m to $191m from a year ago.