BlackRock Sees ETF Crunch Even as Assets Reach $6.3 Trillion

"Sustaining growth at double-digits in terms of asset flows will be really tough to do" for BlackRock, said Kyle Sanders, an analyst at Edward Jones & Co.

Still, analysts say that BlackRock's ETFs held up well given the circumstances of the markets. Advisers continued to allocate money to the products.

"It shows that these passive structures are here to stay and people will buy them whether the market is good or bad," said Sanders.

Fink said during the earnings call he expects ETFs to double in size over the next three to five years.

As BlackRock's less expensive ETFs continue to capture most of the money, that could put pressure on revenue. In October 2016, the firm reduced prices on 15 core ETFs aimed at price sensitive retail clients and financial advisers. The money manager is betting that it can offset any fee cuts with greater volume.

"I think that is why in the short-term seeing money go to this low-cost stuff might be tough, but it sets them up better for the future," said Bloomberg Intelligence analyst Eric Balchunas.

With a good chunk of its assets sitting in passive, BlackRock is trying to diversify into higher-fee alternative offerings and building out its technology business. The firm is depending on its risk-management system, known as Aladdin, to help with its technology push.