BlackRock Inc. BLK reported adjusted earnings of $5.24 per share in the second quarter of 2017, lagging the Zacks Consensus Estimate of $5.39 and improving 10% from the year-ago quarter. A solid improvement in assets under management (AUM) seems to have spurred the earnings beat (read: Why Bank ETFs Fell on Friday Despite Decent Earnings?).The company witnessed strong inflows during the quarter. ETF investors should be happy to know that BlackRock’s assets under management surpassed $5.68 trillion at the end of second-quarter 2017 (up 16%), mainly due to soaring sales of its iShares exchange traded funds. It managed to attract $104 billion of inflows into its funds in the second quarter, as per an article published on Financial Times.Though the world’s largest asset manager’s revenues increased 6% year over year to $2.97 billion. The rise was due to increase in investment advisory, administration fees and securities lending revenues, and technology and risk management revenues. The reported figure was in line with the Zacks Consensus Estimate.What Led to BlackRock’s Strong ETF Inflows BlackRock entered into the battle of fee cuts in recent times having slashed expense fees for some of its iShares ETFs. It is being said that the company took the step to provide tough competition to other low-cost players like Vanguard and Schwab (read: 6 ETF Trends Likely to Take Centre Stage in 2017).For example, BlackRock lowered fees for its S&P 500 tracking ETF, iShares Core S&P 500 IVV, from 0.07% to 0.04%. The fee cut made IVV less expensive than other popular ETFs in its domain. Other two popular S&P 500 ETFs namely SPDR S&P 500 ETF SPY and Vanguard S&P 500 ETF VOO charge 9 bps and 5 bps respectively (read: Buy These ETFs as BlackRock Cuts Fees).Most interestingly, despite the fee cut, BlackRock has managed to maintain its adjusted operating margin at 43.9%, or equal to the same period last year, as per FT.com. Overall, the iShares family of exchange-traded funds, which track almost all the key indexes, hold the key to BlackRock’s success (read: BlackRock Slashes Fees, ETF Price War Intensifies).ETFs in focusLet’s take a look at Q2 inflows (as per etf.com) for some iShares ETFs that have undergone fee cuts lately.iShares Core S&P 500 ETF IVV – $10.85 billioniShares Core S&P Total Stock Market ETF ITOT– $1.39 billioniShares Core S&P Mid-Cap ETF IJH – $423.6 millioniShares Core S&P Small-Cap ETF IJR – $135.0 millioniShares Core MSCI Total International Stock ETF IXUS – $1.25 billioniShares Core MSCI EAFE ETF IEFA – $6.07 billioniShares Core MSCI Emerging Markets ETF IEMG – $4.36 billioniShares Core U.S. Aggregate Bond ETF AGG – $3.73 billionWant key ETF info delivered straight to your inbox?Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report BlackRock, Inc. (BLK): Free Stock Analysis Report SPDR-SP 500 TR (SPY): ETF Research Reports ISHARS-SP SC600 (IJR): ETF Research Reports VANGD-SP5 ETF (VOO): ETF Research Reports ISHARS-SP500 (IVV): ETF Research Reports ISHARS-SP MID (IJH): ETF Research Reports ISHARS-CR US AG (AGG): ETF Research Reports ISHARS-1500 IDX (ITOT): ETF Research Reports ISHARS-CR MS EA (IEFA): ETF Research Reports ISHARS-CR MS EM (IEMG): ETF Research Reports ISHARS-CR INT S (IXUS): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report