Investors' growing appetites for fixed-income exchange-traded funds once again fueled BlackRock Inc.'s latest earnings results.

The world's largest asset manager saw $57.31 billion flow into its bond ETF products during the second quarter, growing assets invested in those products to more than $600 billion — and across the entire company to back above $7 trillion. The record activity around fixed-income ETFs helped drive BlackRock's 21% year-over-year jump in quarterly profits, as asset managers collect a fee on the money their clients invest with them.

"We obviously have big ambitions for fixed-income ETFs. And this last quarter has validated that this is an important asset class, core fixed income, going forward," CFO Gary Shedlin said July 17 during an earnings conference call. "More directly, investors of all kinds have more confidence in fixed-income ETFs than ever before following the extreme test in the first quarter."

A year ago, BlackRock Chairman and CEO Larry Fink proclaimed that assets invested in fixed-income ETFs around the world would swell to $2 trillion by 2024, marking a considerable bet for the asset manager. The environment is well on its way, with fixed-income ETF assets already totaling $1.3 trillion at the end of June, Shedlin said.

BlackRock has so far seen rising demand from both institutional and retail investors in its fixed-income ETF product suite, said Shedlin, who pointed out that there has been "a notable acceleration in adoption from wealth managers, asset managers, pension funds and insurance companies." In a July report published by BlackRock, the asset management behemoth said its fixed-income ETFs were a source of "deep liquidity, continuous price transparency and lower transaction costs than were available in individual bonds."

"Through extreme market turbulence, they functioned incredibly well, which is unlocking a new source of client demand globally," Fink said of fixed-income ETFs on the call.

BlackRock's shares popped after the market's open July 17, rising 3.72% to $588.06 as of 10:58 a.m. ET.